Infant’s finger has a fast-growing nodule

THE CASE

Anxious parents of a healthy 4-month-old boy come to the office for an urgent consultation for a pink nodule on the baby’s fifth finger that has doubled in size over the last month.

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DERMCASE diagnosis: Infantile digital fibromatosis

Overview

Infantile digital fibromatosis (IDF) is a rare, benign fibroproliferative tumor involving the fingers and toes, usually manifesting in the first year of life. These lesions characteristically spare the thumb and great toe, appearing on the dorsal aspect of the digits as single or multiple, smooth, round, reddish-pink nodules.^1,2

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Slow growth of the lesion is seen in the first month, followed by rapid growth over the next 10 to 14 months.³ Spontaneous regression without scarring usually occurs after 2 to 3 years but may take up to 10 years in some cases.^1,3

An IDF is typically less than 2 cm in diameter, nonpruritic, and nontender, with functional impairment and deformities being rare.^1,4 Over 250 cases have been reported in the literature to date, with a third of cases present at birth. There has been only 1 adult case reported in a 52-year-old woman who developed a lesion on her right second toe at the dorsum of the proximal nail fold.^1,4

Etiology

The etiology of IDF is unknown, but there is a prevailing hypothesis of the spontaneous dysfunctional differentiation of fibroblasts into myofibroblasts.⁵

Differential diagnosis

Differential diagnosis should include keloids, juvenile palmoplantar fibromatoses, terminal osseous dysplasia with pigmentary defects, and pachydermodactyly.^3,6 Infantile digital fibromatosis can be differentiated from these disorders based on clinical findings. For definitive diagnosis, a skin biopsy for histopathology revealing myofibroblast proliferation with eosinophilic inclusion bodies is pathognomonic for this condition.^1,2,6

Management

Because of the tendency toward spontaneous involution and frequent recurrence after surgery, observation is the key approach for clinicians in the management of a child with IDF. Parents should be made aware of the benign course of this fibrous tumor. Given the cosmetic requirements of the parents or functional impairment of IDF as indicators for surgical intervention, Mohs micrographic surgery may be a viable alternative to local wide excision with minimization for chance of regrowth and decreased potential for scarring.^1,2

Patient outcome

The IDF on the child’s distal right fifth phalange was asymptomatic, causing no functional impairment. The parents were reassured by the diagnosis, and shave biopsy was done for confirmation. Long-term follow-up will be undertaken to monitor for recurrence of the lesion.

REFERENCES

1. Failla V, Wauters O, Nikkels-Tassoudji N, Cartier A, André J, Nikkels AF. Congenital infantile digital fibromatosis: a case report and review of the literature. Rare Tumors. 2009;1(2):e47.

2. Liu B, Xu ZC, Bao PQ, Hu TZ, Li Y. A case of infantile digital fibromatosis: differential diagnosis and treatment. Int J Dermatol. 2014;53(1):e16-e18.

3. Niamba P, Léauté-Labrèze C, Boralevi F, et al. Further documentation of spontaneous regression of infantile digital fibromatosis. Pediatr Dermatol. 2007;24(3):280-284.

4. Heymann WR. Infantile digital fibromatosis. J Am Acad Dermatol. 2008;59(1):122-123.

5. Spingardi O, Zoccolan A, Venturino E. Infantile digital fibromatosis: our experience and long-term results. Chir Main. 2011;30(1):62-65.

6. Laskin WB, Miettinen M, Fetsch JF. Infantile digital fibroma/fibromatosis: a clinicopathologic and immunohistochemical study of 69 tumors from 57 patients with long-term follow-up. Am J Surg Pathol. 2009;33(1):1-13.

Dr Awosika is a PGY-1 resident at the University of Maryland Mercy Medical Center, Baltimore. Dr Cohen, section editor for Dermcase, is professor of pediatrics and dermatology, Johns Hopkins University School of Medicine, Baltimore, Maryland. The author 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.