Pigmented Plaque with Hypertrichosis on the Scalp of an Infant

Congenital smooth muscle hamartoma on the scalp

“…Although excessive hairiness is the most frequent sign of CSMH, lesions in the head and neck region have rarely been reported in the literature. Only two reports have described CSMH on the head, one of which was located on the frontal scalp and the other on the face 4,5 . In our case, the lesion appeared over the whole scalp and, interestingly, the margin of the lesion did not cross the line of the scalp hair.…”

“…Histology is characterized by the presence of numerous smooth muscle fibers disseminated in the dermis and diversely oriented, sometimes in contact with hair follicles which retain their normal morphology. The clinical differential diagnosis of CSMH includes congenital melanocytic nevus, Becker's nevus, solitary mastocytoma, piloleiomyoma, café‐au‐lait spots, nevus pilosus, and occult spinal dysraphism 2,5 …”

Multiple acquired smooth muscle hamartomas with thick‐walled blood vessels on scalp

“…Günlemez et al reported a case of CSMH of scalp in an 8‐day‐old male infant who presented with a hyperpigmented, slightly elevated plaque with abundant, dark hairs confined to the whole scalp, which on histopathological examination showed features of SMH . Knable and Treadwell documented a 7‐week‐old white boy with a pigmented, hypertrichotic nodule on the scalp since birth, which was diagnosed as CSMH …”