Eva Ilse Rubio, MD

Histopathological slides (low-power, A; high-power, B)from the patient presented in case 1 showed heavy infiltrates inthe lamina propria of the esophagus consisting of lymphocyticplasma infiltrate interspersed with eosinophilic infiltrates. Normal esophageal mucosa (C) is shown for comparison

1. A 4-year-old girl was brought to the emergency department by her parents on a Sunday afternoon. Because of a clinical history of right upper quadrant pain and trace hematuria, abdominal radiographs were obtained. What do they show?

. Early or incomplete small-bowel obstruction.

. Nothing . . . the findings are completely normal. 

2. Based on the radiographic findings, ultrasonography of the kidneys was performed (with a peek at the gallbladder). Both the kidneys and the gallbladder were normal, without nephrolithiasis or cholelithiasis. Nevertheless, the patient still had significant right upper quadrant pain. What study would you order next?

Contrast enema, which will be diagnostic and therapeutic.

3. A limited CT scan of the upper abdomen was obtained. What are the findings in the upper abdomen?

 Liver calcifications; consider parasitic disease.

Rib fractures in various stages of healing.

4. Do the findings on the CT images explain her symptoms, now described as "pain on the entire right side of her body"?

5. One more study was obtained. Do the images explain the patient's right upper quadrant pain?

1. What do the abdominal radiographs show? (C is the correct choice.) Coarse clustered calcifications are seen in the right renal/ suprarenal area. 

The bowel gas pattern is otherwise unremarkable. There is a moderate stool volume in the descending colon and rectum- much for a 4-year-old child-although this is not extraordinary. Bowel obstruction is not depicted

2. Ultrasonography showed normal kidneys and gallbladder, without nephrolithiasis or cholelithiasis. What test would you order next? (A is the correct choice.)

 Here the workup gets a little murky. Because the patient had right upper quadrant pain and trace hematuria, ultrasonography of the kidneys was performed in hopes that it would demonstrate the calcifications in a small adrenal gland or in the kidney-or perhaps in the gallbladder. Nephrolithiasis was thought to be less likely based on the radiographs, which demonstrate a fairly classic appearance for adrenal calcifications-an incidental finding probably resulting from a remote insult (such as a hemorrhage). However, the sonograms eliminated cholelithiasis and nephrolithiasis as possible causes of her symptoms, and we were still unable to locate the calcifications.

At this point, limited unenhanced CT of the upper abdomen was performed to characterize the calcifications once and for all.

Answers & Discussion, Questions 3, 4, and 5

 What are the findings in the upper abdomen? (D is the correct choice.)

Whether the CT scan was absolutely necessary in this patient's case is open to debate; however, this is in fact how the saga unfolded. Indeed, in the right suprarenal fossa are dystrophic, benign-appearing calcifications scattered throughout the right adrenal gland, which is of normal contour and size. There were no renal or liver calcifications, nor were there any rib fractures. It would be unwise to rely on a CT scan to show gallstones, if they were present. CT is notoriously misleading in this regard. Because gallstones vary in composition and density, they may be present but completely inapparent on CT scans. However, we had already eliminated this possibility on the sonogram. 

4. Do the findings on the CT scan explain the patient's symptoms, now described as "pain on the entire right side of her body"? (B is the correct choice.)

5. One more study was obtained. (Perhaps you already thought to order it, back at Question 2.) Do these images explain the patient's right upper quadrant pain? (A is the correct choice.)

The chest radiographs reveal the culprit. The patient has a dense right upper lobe infiltrate. Her pneumonia presented as acute abdominal pain-a known confounder in evaluation of a child who is ill with pneumonia. Many times this phenomenon is seen with a lower lung infiltrate, which is then detected at the upper portion of the abdominal radiographs. The films should always include the lung bases. In this child's case, the upper lobe pneumonia was just beyond the upper edge of the abdominal images. Even when we reviewed the scout image from the abdominal CT scan, the infiltrate could not be seen. (

Articles

1. A 4-year-old girl was brought to the emergency department by her parents on a Sunday afternoon. Because of a clinical history of right upper quadrant pain and trace hematuria, abdominal radiographs were obtained. What do they show?  

Radiology Quiz

 An otherwise healthy 9-month-old girl was brought to the emergency department (ED) by her parents who reported a 12-hour history of nonbloody, nonbilious emesis. The patient had a mildly increased temperature and appeared to be dehydrated. 

These radiographs were obtained approximately 48 hours after the girl's initial presentation to the ED (

Figure 1 - These are supine and lateral decubitus views of the abdomen of a 9-month-old child who presented with a 12-hour history of nonbloody, nonbilious emesis. 

1. What is your interpretation of these images?

 
 A. Mid to distal large-bowel obstruction, with incidentally noted foreign bodies. 
 B. Small-bowel obstruction, with perforation, with incidentally noted foreign bodies. 
 C. Small-bowel obstruction, with suspicious foreign bodies. 
 D. Colonic obstruction, with metallic decorations of the patient's clothing projecting over the abdomen. 



2. What imaging study would you request next?

 
 A. CT scan, to determine the location of the foreign bodies. 
 B. Ultrasonography, to determine the cause of the bowel obstruction. 
 C. No further imaging is needed. 



 3. What is your impression of the bones?

 
 A. The bones are normal. 
 B. There is evidence suggesting nonaccidental trauma. 
 C. There is evidence of chronic lead ingestion. 

1. What is your interpretation of these images? (C is the correct choice.)

These films show 3 loops of distended bowel in the midabdomen. The central location of the loops and their wall contour leave us fairly certain that these are loops of small bowel rather than colon. In particular, note the "stack of coins" appearance of the most superiorly located loop of bowel-a typical appearance for jejunum 

. There is a small amount of air in the stomach and a very small amount of air and stool in the rectum 

Figure 2 - The "stack of coins" appearance of the most superiorly located loop of bowel is a typical appearance for jejunum (A). Image B is a close-up view of jejunum; it shows a small amount of air in the stomach and a very small amount of air and stool in the rectum. These findings can be interpreted as a highgrade or complete mechanical small-bowel obstruction. 

a high-grade or complete mechanical small-bowel obstruction.

To evaluate for free air, it is helpful to have some sort of additional horizontal x-ray beam study. This means an upright, decubitus, or cross-table lateral radiograph to see where free air rises to the highest point of the peritoneal cavity. In this patient's case, the images do not clearly demonstrate free intraperitoneal air. A few modest air bubbles are seen in the right upper quadrant by the inferior tip of the liver 

 on the decubitus view. These most likely reside within the hepatic flexure of the colon, because free intraperitoneal air often has a more crescentic contour. 

 provides a good example of the typical crescentic contour of pneumoperitoneum.

Figure 3 - A few air bubbles are seen in the right upper quadrant by the inferior tip of the liver on the decubitus view. These most likely reside within the hepatic flexure of the colon, because free intraperitoneal air often has a more crescentic contour.

Figure 4 - A decubitus view in another patient demonstrates the typical crescentic contour of pneumoperitoneum. 

Let's turn our attention to the clustered metallic densities that project over the midabdomen. It is interesting (and relevant) that the clumped objects shift slightly 

 when the patient changes from the supine to the decubitus position. However, the objects themselves retain the same orientation to each other from one image to the next. If you have already concluded that these objects are inside the patient and not in a pocket of the patient's clothing, then this restricted motion of the objects becomes more suspect-particularly in the setting of a small-bowel obstruction. We now know that the metallic objects are within the abdomen, but they are not coursing through the bowel and heading for freedom from below. They are stuck.

2. What imaging study would you order next? (C is the correct choice.)

, will add no further information that will affect the patient's immediate treatment, and will only delay her inevitable trip to the operating room. The bowel is obstructed and the multiple ingested metallic foreign bodies that remain stubbornly clumped together are magnets. Magnets that reside in neighboring loops of bowel are still attracted to each other. The soft, thin loops of bowel that are trapped between the magnets suffer pressure necrosis and frank perforation. These magnets will not pass on their own, and surgery is the only solution.

Intraoperatively, 6 magnets and 1 watch battery were found in this child. There was a significant amount of turbid fluid within the peritoneal cavity, several areas of perforation, and a small-bowel to small-bowel fistula. A small segment of small bowel was resected.

The child recovered quickly and was discharged on the fourth postoperative day.

3. What is your impression of the bones? (A is the correct choice.)

, as are the inferior cardiac silhouette and the visualized lung bases-other important things to look at on any abdominal radiograph. The child's bones demonstrate appropriate mineralization and developmental stage.

Findings of lead ingestion-not seen here-would include bright flecks within the stomach or bowel and, in a chronic setting, may result in the finding of dense metaphyseal bands. (The latter has its own differential list that is beyond the scope of this discussion.) Bright flecks within the bowel are a nonspecific finding and may be seen after ingestion of vitamins, medications, and even some candies. Even a hard, long-standing stool ball may start to develop a mildly dense appearance. There is no evidence here to suggest heavy metal ingestion, however.

Mechanical Small-Bowel Obstruction

These images were obtained from a 5-month-old boy who was brought to the emergency department (ED) by his parents who noted new-onset rectal prolapse. The prolapse promptly recurred following initial successful reduction under sedation in the ED. A surgical consultation was obtained and abdominal radiographs were requested.

 1. What is your impression of the bowel gas pattern?

 
 A. There is a soft tissue mound surrounded by a crescent of air, consistent with intussusception. 
 B. There is a mild focal ileus, but otherwise this is a nonobstructive bowel gas pattern. 
 C. The patient is constipated. 
 D. There is a small-bowel obstruction. 



2. Closer inspection of the soft tissues reveals . . . 


 A. Abdominal situs inversus. 
 B. A distended urinary bladder. 
 C. No significant abnormality. 
 D. A left lower quadrant mass. 



 
 A. Osseous abnormalities. 
 B. Cardiomegaly. 
 C. Basilar pneumonia. 
 D. Pneumoperitoneum.



1. What is your impression of the bowel gas pattern? (B is the correct choice.)

The images show a nonobstructive bowel gas pattern. There is an air-filled loop of jejunum in the central abdomen slightly off to the right, best seen on the supine anteroposterior view. The caliber of this loop of bowel is mildly prominent but overall not alarming. There is air in the colon and cecum, and therefore a diagnosis of intussusception is unlikely. There are no significant air-fluid levels on the decubitus view. There is no pneumoperitoneum or pneumatosis.

2. Closer examination of the soft tissues reveals no significant abnormality. (C is correct.)

The soft tissue contours of the liver and spleen are perfectly unremarkable on the supine view. Because the contour of the liver may vary somewhat from patient to patient, I find it tricky to "diagnose" hepatomegaly based on radiographs alone. There are no established charts for the size of the liver according to patient age or weight (as there are for the spleen).

There are also no abnormal masses or calcifications on these images. There is no evidence to suggest urinary bladder distention or other pelvic mass.

3. The radiographs show no evidence of cardiomegaly, basilar pneumonia, or pneumoperitoneum. However, there are unexpected osseous abnormalities in the form of rib fractures. (Option A is correct.)

"Other findings" in the radiographs divert the focus from a simple rectal prolapse reduction to the possibility of child abuse. Careful inspection of the ribs reveals multiple bilateral anterior and posterior rib fractures in varying stages of healing (Figures 1 and 2). This is one of the most highly specific radiological findings of child abuse. The posterior rib fractures are particularly suspect, because essentially no other mechanism besides squeezing of the infant chest results in this fracture in a healthy child. Other fractures that are highly specific for child abuse include the classic metaphyseal corner fracture, scapular fractures, spinous process fractures, and sternal fractures.

Figure 1 - Magnified view of the ribs: there are multiple bilateral anterior, posterior, and lateral rib fractures with varying degrees of callus.

Figure 2 - Skeletal survey of the same child with oblique views reveals more rib fractures. Oblique views are not always included as part of the  outine skeletal survery but may be useful in  etecting additional fractures not seen on the  anteroposterior and lateral views of the chest. 

Any fracture that is inconsistent with the child's stage of development (a child cannot sustain a toddler's fracture if they don't toddle) and any fracture that would require a mechanism that is inconsistent with the reported history should prompt consideration of nonaccidental trauma. Rolling off of a couch does not result in multiple bruises and a displaced skull fracture.

 Abuse and neglect are responsible for approximately 1200 deaths in the United States each year.

 Children younger than 1 year are by far the most vulnerable: they account for slightly less than half of all abuse-related fatalities. Radiographic and physical evidence of abuse is sometimes quite obvious, but at other times can be quite subtle; rib fractures may be subtle or inapparent and may not be accompanied by chest wall bruising.

It is incumbent on all of us-clinicians, radiologists, family, and friends- not to miss evidence of abuse. 

The American College of Radiology offers detailed guidelines for obtaining a complete skeletal survey, which specifies 19 standard images at a minimum.

 Additional images may be obtained as deemed necessary, particularly if there are questionable areas that deserve further evaluation. A follow-up skeletal survey in 10 to 14 days is an important option to consider, because some acute fractures may be very difficult to detect initially but will become more apparent as callus formation commences.

CNS imaging findings commonly seen in child abuse include subdural hematomas, axonal shear-type injury, focal or global ischemia, contusions, compression fractures of the spine, and skull fractures. Retinal hemorrhages may be documented by an ophthalmologist but often are not apparent on cross-sectional imaging such as CT or MRI.

Successful detection of child abuse requires close cooperation among many people involved in the evaluation and care of a child. Any individual may be the one to tip us off to abuse-the social worker in the ED who notes conflicting stories, the emergency or primary care physician who observes suspicious bruises, or the radiologist who identifies unsuspected rib fractures. The safety of our children, of course, always comes first.

Lonergan GJ, Baker AM, Morey MK, Boos SC. From the archives of the Armed Forces Institute of Pathology (AFIP). Child abuse: radiologic-pathologic correlation. Radiographics. 2003;23:811-845. 

Cadzow SP, Armstrong KL. Rib fractures in infants: red alert! The clinical features, investigations and child protection outcomes. J Paediatr Child Health. 2000;36:322-326. 

ACR practice guideline for skeletal surveys in children. Available at: http:// www.acr.org/SecondaryMainMenuCategories/quality_safety/guidelines/ pediatric/skeletal_surveys.aspx. Accessed January 18, 2008. 

Caffey J. Multiple fractures in the long bones of infants suffering from chronic subdural hematoma. AJR. 1946;56:163-173. 

Falcone RA, Brown RL, Garcia VF. Disparities in child abuse mortality are not explained by injury severity. J Pediatr Surg. 2007;42:1031-1037. 

Hudson M, Kaplan R. Clinical response to child abuse. Pediatr Clin North Am. 2006;53:27-39. 

Sugar NF, Taylor JA, Feldman KW. Bruises in infants and toddlers: those who don’t cruise rarely bruise. Puget Sound Pediatric Research Network. Arch Pediatr Adolesc Med. 1999;153:399-403. 

Radiographic Findings in Child Abuse

1. The chest radiographs (Figure 1) of a 9-year-old child reflect the classic findings of a particular disease. Among other findings, the size of the patient's heart is_____?

2. If you were to see calcifications in the abdomen (none are present in this case), they would probably be caused by which of the following?

5. Which of the following organisms are common culprits in this condition?

(Answers and discussion begin on page 28.)

Answer & Discussion: The radiographs show classic findings of cystic fibrosis (CF).

1. The chest radiographs (see Figure 1) of a 9-year-old child reflect the classic radiographic appearance of CF. Among other findings, the size of the patient's heart is 

The patient's heart is probably of normal size, but the hyperexpansion commonly seen in patients with CF may make it seem relatively small. This phenomenon is frequently observed in older patients with emphysematous lungs. A small cardiac silhouette may also be seen in patients with asthma. The finding of microcardia could also suggest a hypovolemic state in other patients.

Other common radiographic and cross-sectional imaging (CT) findings of CF include focal atelectasis with or without hyperaeration, bronchiectasis seen as dilated tubular tracts or end-on with a cystic appearance, parahilar streaky opacities, peribronchial thickening, and mucous plugging.

Remember that patients with advanced CF may have enlarged pulmonary arteries from pulmonary arterial hypertension. Furthermore, copious hemoptysis is an uncommon but life-threatening development when pulmonary pathology encroaches on neighboring bronchial arteries, which themselves often demonstrate compensatory enlargement and tortuosity.

Other findings of end-stage CF include emphysema, pneumothorax, and cor pulmonale. Hypertrophic pulmonary osteoarthropathy is another rare entity that may be seen but is beyond the scope of this discussion.

2. If you were to see calcifications in the abdomen (none are present in this case), they would probably be caused by 

Patients with CF not infrequently experience gallbladder complications, such as stones, which may be apparent on plain radiographs. The gallbladder of a patient with CF may also be small, contain sludge, demonstrate poor contractility, or manifest chronic inflammation.

Other GI problems related to CF include endocrine and exocrine pancreatic insufficiency (many patients are insulin-dependent), fatty infiltration of the liver, frank cirrhosis, and uncomplicated or complicated meconium ileus. The list of GI complications also includes meconium ileus equivalent (now called distal intestinal syndrome), gastroesophageal reflux disease, mucous distention of the appendix, intussusception, rectal prolapse, and colonic strictures. The development of colonic strictures in patients with CF has a strong association with use of high-strength pancreatic supplements. Many of the other manifestations of CF in the GI tract ultimately can be traced back to a common origin of inspissated mucus and its tendency to obstruct smaller channels.

3. Is there evidence of hyperinflation? The answer is 

If the frontal view isn't enough to persuade you (count the 10 to 11 posterior ribs on the frontal view), take a look at the lateral view. The diaphragms are nearly completely flattened and there is a barrel shape appearance to the chest that results from anterior expansion (the anterior clear space) and bowing.

It can be difficult to tell whether there are acute findings on a particular single radiograph when seen in isolation. Careful comparison with earlier chest radiographs is essential to determine which area of parenchymal opacification is new amid the scarring, atelectasis, and architectural distortion. Sometimes acute findings (such as an acute lobar pneumonia)are obvious; often enough, they are not. This is why radiologists refer to the comparison radiograph as their "best friend." ("Old is gold.")

) was interpreted without the benefit of earlier films at our institution. 

Thus, the presence of acute findings cannot be determined. (C is the correct choice.) 

Although no acute findings are suspected, a more confident interpretation would be possible if earlier films had been submitted for comparison. 

A chest CT scan obtained several weeks later (

) demonstrates in more detail the bronchiectasis and hyperinflation seen on the radiographs. Note the thickened walls of the airways, which can also be appreciated on the lateral view of the initial radiographs. Look for the fuzzy "cheerios," which represent the airways seen end-on, with thickened/inflamed walls.

5. Which of the following organisms are common culprits in CF? 

Pseudomonas aeruginosa, Burkholderia cepacia,

 are among the pathogens commonly associated with CF. (D is the correct answer.)

We all learned early on that CF is associated with 

infection. The pathogen involved is not garden-variety 

 however: it is a sticky mucoid variant that most patients with CF harbor indefinitely. Occasionally, infectious exacerbations are beaten back into submission with antibiotic therapy.

The frequency and duration of pulmonary infections affects decisions about vascular access. In the patient featured in this case, a chest port was placed in anticipation of long-term access needs.

Other infections that commonly afflict patients with CF are 

B cepacia, S aureus, Haemophilus influenzae, Stenostrophomonas maltophilia, 

in its allergic form, which results in extensive mucous plugging of the airways. Non-tuberculous mycobacteria has also emerged as a problem for those with CF.

The life expectancy of patients with CF continues to improve; in the earlier part of the 20th century many CF patients did not live to see their 10th birthday. Today, many patients survive into their 40s. Early diagnosis and attentive clinical management make a big difference in the lives of these patients.

From a genetic standpoint, CF is __________________?

While most clinicians know that CF is an 

autosomal recessive disorder (A is correct) 

that affects the cells' chloride channel (the most common mutation to the cystic fibrosis transmembrane regulator [CFTR] is known as delta F508), it is also useful to remember that there are numerous variations of the specific genetic defect and plenty of variability in the phenotypic expression as well. Some patients have primarily GI complications, and the severity of pulmonary disease is also highly variable. A small percentage of patients retain a certain degree of pancreatic function.	*

Radiographic Findings in Cystic Fibrosis

Frontal and lateral views of an 11-year-old girl's chest are shown here (Figure 1). What are the findings in the lungs?

Excluding the central line, these images demonstrate evidence for involvement of 3 organ systems. What are they?

 Cardiovascular, genitourinary, and bone.

An image from the patient's MRI brain scan is shown in Figure 2. It demonstrates expansion of what space?

(Answers and discussion begin on the next page.)

Figure 1 shows the frontal and lateral views of an 11-year-old girl's chest. What are the findings in the lungs?

It is always tempting to find something on the chest radiograph that might explain a patient's symptoms. In this instance, however, there are no pathological findings in the lung parenchyma.

These images demonstrate evidence for involvement of which 3 organ systems?

These images provide us with 3 clues about this child's underlying medical condition. First, her cardiac silhouette is a little too generous. On the frontal upright anteroposterior view, her greatest cardiac diameter is 60% of her greatest thoracic diameter. By age 11 and by the looks of her superior mediastinum, this enlarged appearance cannot be attributed to a prominent thymus. (By approximately age 10, the thymus should no longer appear particularly noticeable on a child's chest radiograph.

) The lateral view confirms the cardiomegaly: the posterior heart border extends quite close to the anterior aspect of the thoracic vertebral bodies.

Possible causes of an enlarged heart in a child include cardiomyopathy, pericardial effusion, high-flow vascular lesions, renal disease, anemia, and congenital heart disease. Congestive heart failure seems unlikely in this case because the pulmonary arteries and veins are normal and there is no pleural effusion. In this child's case, anemia with elevated cardiac output is the culprit, as evidenced by the cardiomegaly.

The second clue to the diagnosis is found in the bones on the lateral view: note the sclerosis and irregular indentation of the vertebral endplates. This is apparent on all of the visualized thoracic and lumbar vertebral bodies and must therefore reflect a diffuse, systemic process rather than something focal, such as trauma or osteomyelitis. In this case, the multiply-affected endplates represent the chronic appearance of vascular insufficiency and/or avascular necrosis.

The third clue is found on the frontal view. A small surgical clip can be seen in the soft tissues of the right upper quadrant--evidence that a surgeon has probably absconded with this patient's gallbladder.

There is cardiovascular, GI, and bone involvement

A fourth clue is the implantable port beneath the patient's skin placed to provide intravenous access when necessary (although technically this is part of the cardiovascular system). 

An image from the patient's MRI brain scan (Figure 2) demonstrates expansion of what space?

This is a T1-weighted image of the same child's brain obtained in the sagittal plane. On a T1-weighted sequence, fat is bright and fluid is dark. The subdural and subarachnoid spaces are normal. 

Look closely at the occiput; under the bright stripe that reflects the normal subcutaneous fat of the scalp's skin, there is a broad, dark stripe that represents noticeable 

). This is a common feature in children with sickle cell disease and is the result of compensatory hematopoiesis. In a healthy child, we would expect that space to be more narrow and also fatty--and therefore bright on T1-weighted images. Instead, the dark, fluid-like signal characteristics of this diploic marrow confirm that this is active, hematopoietic marrow. This preservation of red marrow and failure to convert to fatty marrow is seen in many areas of the skeleton of a patient with sickle cell disease and often persists throughout a patient's lifetime.

Other typical osseous findings of sickle cell disease include avascular necrosis of the humeral and femoral heads; intramedullary bone infarctions almost anywhere, including the ribs and bones of the hands; and osteomyelitis. Osteomyelitis is a less common event in sickle cell patients than bone infarction, but it may be very difficult to differentiate the 2 entities because there is a significant degree of overlap in clinical, radiological, and laboratory findings.

 Causative organisms of osteomyelitis in this patient population include 

and assorted Gram-negative enteric bacilli.

shows an earlier chest radiograph from this same child. It was taken 2 years earlier, when she presented with fever, hypoxia, and chest pain. At that time, a diagnosis of acute chest syndrome (ACS) was made. A nuclear medicine bone scan obtained at that time (

) revealed a mottled appearance of the ribs, reflecting alternating areas of increased or decreased uptake of the radiotracer by the osteoblasts, consistent with scattered bone infarcts of the ribs of varying ages. The calvarium is thickened on the bone scan too--a finding consistent with expansion of the diploic space.

ACS remains a common cause of morbidity and mortality among patients with sickle cell disease. Recurrent episodes are frequent. Thus, ACS is a leading cause of hospitalization--and is often cited as the leading cause of death--in children with this disease.

 The diagnosis is made by identifying a new infiltrate on radiographs, along with dyspnea, fever, leukocytosis, cough, pain, or hypoxia.

ACS is generally thought to be a multifactorial entity caused by various combinations of infection, rib infarction, chest splinting from pain, and thromboembolic events to the lungs.

 The pulmonary intravascular events include in situ thrombosis with sickling, acute and chronic thrombi, and fat emboli originating from bone infarctions.

Most cases of ACS do not have a clear cause. When infection appears to be the predominant process, the common pathogens include 

Streptococcus pneumoniae, Haemophilus influenzae, S aureus, Chlamydia pneumoniae, 

 Chest radiographs commonly show multifocal disease, especially in the lower lobes.

 Differentiating between infection and infarction in the lung may be difficult. Some reports suggest that an upper lobe process is more likely to represent an infection, whereas lower lobe processes may be more likely to represent infarction.

ACS places patients at increased risk for the chronic pulmonary manifestations of sickle cell disease, which include pulmonary hypertension, ventilatory compromise, and cor pulmonale.

Pulmonary hypertension in children with sickle cell disease is associated with significant morbidity; pulmonary hypertension in adults with sickle cell disease has high rates of both morbidity and mortality.

 Kirks D. Respiratory system. In: Kirks DR, Griscom NT. 

Practical Pediatric Imaging: Diagnostic Radiology of Infants and Children. 

3rd ed. Philadelphia: Lippincott-Raven; 1998: 619-819.

 Melton CW, Haynes J Jr. Sickle acute lung injury: role of prevention and early aggressive intervention strategies on outcome. 

 Lonergan GJ, Cline DB, Abbondanzo SL. Sickle cell anemia. 

Martin L, Buonomo C. Acute chest syndrome of sickle cell disease: radiographic and clinical analysis of 70 cases. 