Hidden Malignancy: Predominantly In Situ Porocarcinoma Arising in a Poroma
Year: 2026
Type: article
Study design: Case Report
Abstract: ABSTRACT: Porocarcinoma is a rare malignant adnexal tumor which can originate either de novo or-much more rarely-from a preexisting eccrine poroma. Given its aggressive clinical behavior, a timely diagnosis is essential for optimal patient's management. We report the case of a 79-year-old woman presenting with a well-circumscribed exophytic mass located on her right calcaneal region, which had been present for 2 years but had recently shown progressive enlargement. An excisional diagnostic biopsy was performed, and histopathological examination showed a poroid lesion with no malignant features. A diagnosis of eccrine poroma was then considered. However, deeper sections revealed a focal intraepidermal proliferation of markedly atypical cells and a small intradermal nest suggestive of early dermal invasion. The atypical population was characterized by overexpression of both p53 and p16, an increased ki-67 proliferation index, and preserved mismatch repair proteins. The diagnosis was then changed into a predominantly in situ , focally invasive porocarcinoma arising in an eccrine poroma. The patient underwent electrocautery of the wound margins and an echographic examination of pelvic nodes-which were negative for metastases-and was free of recurrence at a 6-month follow-up. This case provides evidence that benign-looking eccrine poromas may harbor microscopic foci of malignant transformation, thus emphasizing the need for a careful and thorough histopathological evaluation of these lesions.
Institutions: Centro Diagnostico Italiano, University of Milano-Bicocca
Language: English
Topic: Cancer and Skin Lesions
Subfield: Dermatology
Field: Medicine
Domain: Health Sciences
Open Access status: hybrid
OpenAlex ID: W7204438201