The parents of a healthy 11-month-old girl eagerly seek a consultation for a recurrent blistering brown bump on the baby’s right cheek, present since birth. Recently, the blistering episodes seem to be decreasing, although the bump continues to become bright red a few times a week.
The parents of a healthy 11-month-old girl eagerly seek a consultation for a recurrent blistering brown bump on the baby’s right cheek present since birth. Recently, the blistering episodes seem to be decreasing, although the bump continues to become bright red a few times a week.
Solitary mastocytoma is recognized as a benign papule or plaque resulting from an infiltration of mast cells in the dermis. Lesions are generally 1 cm to 5 cm in diameter and can be present at birth or develop in the first few months of life (Figure 1).
Initially, the papules are flesh colored, but they may become pink, yellow, tan, or golden brown within
3 to 6 months.1 Although the rubbery papules or plaques resolve in 5 to
10 years, the pigment may persist for 2 decades or longer. Urtication with erythema and edema may occur following trauma or sudden environmental changes such as changes in temperature. Vesiculation may occur in the first 2 years of life simply as a result of increased skin fragility at that age.1 The palms, soles, face, and mucus membranes are often spared.
The differential diagnosis includes fixed drug eruption, herpes simplex virus, recurrent bullous impetigo, congenital melanocytic nevus, and juvenile xanthogranuloma.1 The diagnosis can be confirmed by rubbing, resulting in the characteristic Darier sign from local histamine release (Figure 2).2
Uncommonly, the patient can experience systemic histamine release with hypotension, flushing, tachycardia, wheezing, abdominal colic, and diarrhea.3 Flushing is the most common presentation.1 Rare complications may include anaphylaxis, especially after stings by Hymenoptera,4 as well as coagulation disorders because mast cells are also laden with heparin.
Treatment consists of oral antihistamines as needed. Oral cromolyn is a medication that is hypothesized to inhibit the degranulation of mast cells, and it may have some effect on the late allergic response by also affecting other cell types.5 It must be used preventively although it is poorly absorbed, and whereas there are case reports of its use in mastocytosis, no strong evidence exists for its use in solitary mastocytomas. Fortunately, most children have minimal or no symptoms requiring treatment and most lesions resolve without intervention.
Affected children should avoid nonsteroidal anti-inflammatory drugs and opiates, as well as iodinated contrast media, which can lead to sudden release of large amounts of histamine.4 Only the rare patients with systemic symptoms or a history of anaphylaxis should carry epinephrine.3
Solitary mastocytomas are part of the broader spectrum of cutaneous mastocytoses, all characterized by varying degrees of mast cell aggregates in the dermis. Solitary mastocytomas represent the least severe cutaneous mastocytosis. More than 1 solitary mastocytoma merits a diagnosis of urticaria pigmentosa.
Diffuse cutaneous mastocytosis (DCM) and telangiectasia macularis eruptive perstans (TMEP) are more severe forms: DCM usually develops in the newborn as thickened, doughy skin and improves with time1; TMEP is rare but usually persistent,4 more localized to the trunk, and it often starts in adolescence or adulthood.1
Solitary mastocytomas and childhood onset urticaria pigmentosa resolve spontaneously in at least 50% of cases and in over 90% of patients.4 Systemic indolent mastocytosis and systemic smoldering mastocytosis, as well as mast cell tumors and myelodysplastic or myeloproliferative conditions involving mast cells, also are extremely rare.6
Mastocytoses reportedly affect no more than 20,000 to 30,000 persons in the United States,2 with a slight female predominance up to 3:1. The incidence of childhood solitary mastocytomas and asymptomatic urticaria pigmentosa may be underestimated. However, based on patient population, the authors believe these are quite common, self-limited conditions of childhood.
The infant in this case did not require any treatment for her solitary benign mastocytoma. Anticipatory guidance was provided that the lesion should self-resolve.
1. Morelli JG. Diseases of the dermis. In: Kliegman RM, Stanton BF, St. Geme JW III, Schor NF, Behrman RE, eds. Nelson Textbook of Pediatrics. 19th ed. Philadelphia, PA: Elsevier/Saunders; 2011:2273-2282.
2. Metcalfe DD. Mastocytosis. In: Adkinson NF Jr, Bochner BS, Burks AW, et al, eds. Middleton's Allergy: Principles and Practice. 8th ed. Philadelphia, PA: Elsevier/Saunders; 2014:1224-1236.
3. Cohen BA, Davis HW, Gehris RP. Dermatology. In: Zitelli BJ, McIntire S, Nowalk AJ. Zitelli and Davis’ Atlas of Pediatric Physical Diagnosis. 6th ed. Philadelphia, PA: Elsevier/Saunders; 2012:299-368.
4. Soter NA. Mastocytoses. In: Lebwohl MG, Heymann WR, Berth-Jones J, Coulson I. Treatment of Skin Disease: Comprehensive Therapeutic Strategies. 4th ed. Philadelphia, PA: Elsevier/Saunders; 2014:443-446.
5. Boushey HA. Drugs used in asthma. In: Katzung BG, Masters SB, Trevor AJ. Basic and Clinical Pharmacology. 11th ed. New York: McGraw Hill Medical; 2009:348-349.
6. Akin C, Valent P. Diagnostic criteria and classification of mastocytosis in 2014. Immunol Allergy Clin North Am. 2014;34(2)207-218.
Dr Peroutka is a pediatrics-genetics resident at Johns Hopkins Hospital, Baltimore, Maryland. Dr Koch is a pediatric dermatology fellow at Johns Hopkins Hospital, Baltimore. Dr Cohen, section editor for Dermcase, is professor of pediatrics and dermatology, Johns Hopkins University School of Medicine, Baltimore. The authors and section editor have nothing to disclose in regard to affiliations with or financial interests in any organizations that may have an interest in any part of this article. Vignettes are based on real cases that have been modified to focus on key teaching points. Images also may be edited or substituted for teaching purposes.