Background: Smooth muscle hamartoma is an uncommon lesion. Diagnosis is usually made at birth in infants presenting a plaque with minimal or no infiltration and covered with long dark hairs. Congenital forms with multiple plaques are rarely reported.
Case report: A 5-day-old infant (normal pregnancy and delivery) had plaques localized on the buttocks, the left thigh, leg and shoulder and the right ankle. The plaques were minimally infiltrative and covered with long black hairs. Histology examination showed hyperplastic smooth muscle bundles with varying orientation. The diagnosis was smooth muscle hamartoma. The rest of the clinical examination was normal.
Conclusion: This case of congenital smooth muscle hamartoma showed a particular form with partially regressive multiple plaques.