Keratoacanthoma Centrifugum Marginatum at an Unusual Site
A 62-year-old male, watchman by occupation presented with asymptomatic raised lesion on scalp since one year. He gave a history of excessive sun exposure but denied prior trauma. Lesion had developed de novo, as a pea sized lesion with gradual increase to cover entire vertex. A surgical intervention done subsequently resulted in development of a non-healing ulcer. He did not have any systemic complaints. Cutaneous examination revealed a single, irregular, 12 × 15 cm, yellowish plaque on vertex of scalp with nodular surface and a central crater []. On palpation, the plaque was firm, non-tender, non-indurated and not attached to underlying structure. Multiple seborrheic keratosis of various sizes were seen on bilateral temple area and forehead. There was no regional and systemic lymphadenopathy. His haemogram, chemistry profile, X-ray chest and skull were normal. CT scan of brain did not show any abnormality. Ultrasonography of lesion showed ill defined hypo echoic mass involving epidermis, dermis and subcutaneous tissue.\nDeep punch biopsy revealed exoendophytic, globular, well circumscribed central cup shaped crater, epidermal invagination with marked hyperkeratosis and horn cyst with rich keratin filled crater imparting glassy appearance and well demarcated regular base. Epidermis formed buttress over the pseudhorn cyst [Figures and ]. Dense nodular lymphocytic infiltrate was seen in the upper dermis []. Deeper dermis, appendegeal structures and subcutaneous tissue were unremarkable. Marked epidermal proliferation with crater formation with horn pearls and inflammatory infiltrate at the base of the lesion was suggestive of a fully developed lesion of KCM. Complete surgical excision with grafting was done successfully with dramatic improvement with no recurrence at 9 months [].