‘Pseudocarcinomatous Changes in Giant Porokeratosis of Mibelli’: Histopathology as a Valuable Asset for Early Recognition of Neoplastic Changes- A Case Report with Review

Porokeratosis is a clonal expansion of keratinocytes which differentiate abnormally but not completely neoplastic in nature. The various types of porokeratosis are characterized by a thin column of parakeratosis, the cornoid lamella, the active border of lesion.

Porokeratosis is listed as a rare disease by Orphanet and the Office of Rare Diseases (ORD) of the National Institute of Health.

Mibelli described the classical form that bears his name (1893). The diagnosis is confirmed by histopathological examination. It may be complicated by development of cutaneous malignancies, like squamous cell carcinoma (most common in linear variant) [1].

Etiopathogenesis of porokeratosis include Ultraviolet light exposure, extensive radiation therapy, immunosuppression, transplant procedures, immunodeficiency syndromes, chronic renal failure, chronic liver disease, infections, hematological malignancies including lymphomas, HIV infection and hepatitis C virus infection [2]. Recent theories suggest that abnormalities in the mevalonate pathway are responsible for the pathogenesis of porokeratosis. Abnormalities in the genes MVD (mevalonate decarboxylase), mevalonate kinase, PMVK (phosphomevalonate kinase), FDPS (farnesyl diphosphate synthase) and solute carrier family 17 member 9 (SLC17A9) have been found to be pathogenic in porokeratosis [3].

This case report addresses a rare case of giant porokeratosis of Mibelli showing features of pseudoepitheliomatous changes raising suspicion of future malignant transformation possibility that was treated with surgical excision of lesion coupled with systemic and topical therapies even though the patient was lost to follow-up.