By Gary M. White, MD
Rhabdomyomatous Mesenchymal Hamartoma (RMH) is an extremely rare congenital lesion made up of striated muscle. Because of this, it may move or contract when the baby feeds.
Initially described as striated muscle hamartoma, this rare disease presents as a solitary or multiple, congenital, facial papulonodule which may be elongated or snake-like in appearance. It contains striated muscle which may cause movement or contraction when the infant feeds or when the older child contracts his facial muscles. Midline lesions of the face and neck are the most common presentations.
Case reports describe lesions appearing in a variety of ways including a purple "vascular" lesion on the lip, a bilobed pedunculated tag on the neck, a papule in the tongue, a subcutaneous nodule, and a 2 cm red polyploid mass emanating from the vagina of a newborn. Multiple lesions have been described. Rhabdomyomatous mesenchymal hamartoma is usually an isolated finding, but various congenital abnormalities have been associated in case reports.
Associated congenital anomalies, including ocular abnormalities, thyroglossal duct sinus, and amniotic band syndrome, occur in approximately 40% of cases [Peds Derm 2016;33;e36].
Spontaneous regression has occurred but is uncommon [West Indian Med J 2009:58;607]. Surgical excision, if feasible, may be done. Since no cases of malignant transformation have been reported, observation is appropriate [Clin and Exp Derm 2013;38;439].
A 15-day-old boy born at 38 weeks of gestation presented with a skin-covered, smooth, polypoid papule measuring 0.7 × 0.5 × 0.5 cm protruding from the chin. JAAD Case Rep. 2016 May; 2(3): 222–223
Peds Dermatology 1986;3;153
Picture of the Month. Am J Dis Child. 1989; 143(8):963-964
Am J Dermatopath 1990;12;485
Am J Dermatopath 1989;11;568
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