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Indian Journal of Dermatology, Venereology and Leprology, Vol. 71, No. 3, May-June, 2005, pp. 217-218 Quiz Hyperpigmented patch on the trunk of a neonate Palit Aparna, Inamadar Arun C., Athanikar S.B., Sampagavi V.V., Deshmukh N.S., Yelikar B.R. Department of Dermatology,Venereology and Leprosy, BLDEAs SBMP Medical College, Hospital and Research Centre, Bijapur Code Number: dv05076 A one-day-old, full-term, normally delivered, female neonate was being routinely examined. A brownish irregular patch of 2 cm
× 1.5 cm, with fine long hairs was observed on her right loin
[Figure - 1]. On gentle stroking, the lesion became more prominent along with the appearance of goose bumps. A punch biopsy was taken from the edge of the lesion. Histopathological preparation on H/E stain showed mild hyperkeratosis of the epidermis and basal cell hyperpigmentation. In the reticular dermis, well-defined smooth muscle fiber bundles were seen, interspersed among hair follicles
[Figure - 2]. Masson Trichrome stain
[Figure - 3] confirmed the presence of smooth muscle fibers (stained red). WHAT IS THE DIAGNOSIS? DISCUSSION CSMH was first described by Stokes in 1923.[1] The lesions may be solitary or multiple, the former being commoner (1 in 3000 births).[2] Classically, it is present at birth or seen during the first week of life, located most commonly over the lumbo-sacral region.[2] Other sites of occurrence are buttocks, proximal extremities, and rarely the scalp.[3] Multiple lesions are rare and may occur in a linear pattern.[4],[5] Diffuse involvement may occur with the Michelin type baby syndrome.[6]The commonest morphological pattern is a skin-colored or slightly hyperpigmented patch or plaque associated with long vellus hairs or small follicular papules all over the lesion.[2] On gentle stroking, the lesion shows vermiculation and pilo-erection (Pseudo-Darier′s sign)[2],[7] or occasionally fasciculation.[2] Lesions occurring as a linear atrophic plaque[4] and a patch with perifollicular papules[5] have been reported. CSMH is related to the arrectores pilorum muscle,[8] which in fetal life originates from a diffuse metachromatic zone of mesoderm situated near the hair germ. Over-proliferation of this region is likely to give rise to the lesion. Clinically, CSMH has to be differentiated from cafι-au-lait macule, solitary mastocytoma, congenital melanocytic nevus and connective tissue nevus.[2] Histopathologically, pilar leiomyoma is an important differential diagnosis.[8] A well-defined bundle of long, straight smooth muscle cells in the deeper dermis, which are separated from the dermal collagen by a clear space, is characteristic of CSMH. Irregular smooth muscle bundles, intermingled with collagen, which may be attached to the hair follicle, are found in pilar leiomyoma.[5],[8] An acquired form of smooth muscle hamartoma without hyperpigmentation or excessive hair has been reported.[9] Other acquired lesions occur in association with Becker′s nevus.[4] There are clinical and histopathological overlaps between Becker′s nevus and CSMH.[7],[8] Some authors include both the entities in a spectrum of hamartomatous disorders,[7] involving the epidermis (hyperpigmentation), hair follicles (hypertrichosis) and the dermis (smooth muscle). Children with the diffuse form of the disease may have other congenital malformations, growth and mental retardation.[7] No treatment is necessary for solitary lesions, which may persist unchanged or there may be slight reduction of the hypertrichosis. REFERENCES
Copyright 2005 - Indian Journal of Dermatology, Venereology and Leprology The following images related to this document are available:Photo images[dv05076f2.jpg] [dv05076f3.jpg] [dv05076f1.jpg] |
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