Malignant eccrine poroma in an unusual location

Abstract

Malignant eccrine poroma is a rare skin appendage tumour, originating from the intraepidermal and upper dermal eccrine ducts. The tumour either arises spontaneously or develops in a long-standing eccrine poroma, generally in elderly people over 60. Clinically, it tends to be a localized lesion, which manifests itself as a nodule or ulcerated tumour, favouring extremities. We report an 83-year-old female with an enlarging and bleeding tumour on her lumbosacral region. This lesion first appeared as a small pigmented papule and progressed to an erythematous patch with central papular portion and some peripheral pigmentation. Histopathology revealed malignant eccrine poroma. Also, immunohistochemically, diffuse and intense p53 staining was observed. Regular pigment pattern, brown globules and black dots were seen in dermoscopic examination. After performing a wide excision, 20 months of follow-up revealed no recurrence or metastasis of the tumour. This case represents an unusually located malignant eccrine poroma with some pigmentation.