Porocarcinoma Arising in Pigmented Hidroacanthoma Simplex

Abstract

Hidroacanthoma simplex (HAS) is a rare benign tumor that is also known as intraepidermal poroma. While there have been a few reports of HAS with malignant transformation (porocarcinoma), we report an unusual case of porocarcinoma, arising in a pigmented HAS, the latter also showing secondary amyloid deposits. An 80-year-old Japanese man presented with a cutaneous tumor on his left buttock, which had first been noticed in his childhood. The tumor consisted of flat pigmented plaque and a depigmented papule with erosion. Histologic analysis revealed many pigmented and well-defined nests within the epidermis of the flat pigmented portion. The nests were composed of cuboidal to oval and occasionally elongated, bland, basaloid cells with numerous melanin granules. In addition, there were infrequently ductal structures and small clusters of sebocytes, and abundant amyloid deposits in the upper dermis. These findings were consistent with pigmented HAS with amyloid deposition. In the depigmented portion, markedly atypical cells with occasional ductal structures and intracytoplasmic lumina extended throughout the entire thickness of the epidermis, with minimal invasion of the dermis. We considered this portion of the tumor to be a porocarcinoma. Since the two portions of the tumor were continuous, we made a final diagnosis of porocarcinoma arising in pre-existing pigmented HAS with amyloid deposition.

Hidroacanthoma simplex: dermoscopy and cryosurgery treatment

“…5-7 Most cases developed from pre-existing long-term HS. Local excision or Mohs micrographic surgery are suggested to avoid this possible progression.…”

A case of hidroacanthoma simplex

“…Sometimes the plaques are easily confused with those of seborrheic keratosis or basal cell carcinoma. [3–5]…”

“…Intracytoplasmic glycogen and occasional ductal structures within the nests of cells are also characteristic of hidroacanthoma simplex. [3–5]…”

Ekkrines Porokarzinom neben multiplen anderen epithelialen Hauttumoren

“…Porokarzinome können de novo, auf dem Boden von ekkrinen Poromen [3], aber auch auf epithelialen Präkanzerosen und Hidroakanthomen entstehen [9,15]. Sie werden -wie im hier vorgestellten Fall -gehäuft in Assoziation mit anderen epithelialen Hauttumoren beobachtet [4,8].…”

“…Auch histologisch können Porokarzinome eine Vielzahl an Merkmalen imitieren, sodass die Diagnose erschwert sein kann [14,15].…”