Keratotic Nodule on The Heel: A Quiz.

A 51-year-old man, with a medical history of medullary thyroid carcinoma excised under thyroxine treatment presented with a painful enlarging lesion on his right heel since one year. A 3-cm diameter, greyish, infiltrated nodule with spicules was seen on physical examination (Fig. 1a). A 5-mm surgical excision was made and a total skin graft was used for reconstruction. Histopathology of the total resected tumour revealed pseudoepitheliomatous hyperplasic epidermis and a proliferation located between rete ridges, dermis and superficial hypodermis (Fig. 1b). The proliferation was composed of nets and cordons of cells with granular and abundant PAS-positive cytoplasm. Immunostains showed cytoplasmic positivity for s100 and inhibin (Fig. 1c). Three years later the patient is asymptomatic.