Eccrine Porocarcinoma: A Challenging Diagnostic and Therapeu
An 82-year-old woman with no major past medical history was referred after undergoing biopsies of longstanding pubic skin lesions. The patient was otherwise feeling well and had no symptoms. Physical examination revealed a 2-cm ulcerated lesion on her pubis. There were no palpable inguinal lymph nodes, and examination of the genital parts was normal. The biopsy results from another medical center came back with a diagnosis of poorly differentiated squamous cell carcinoma on all the samples. The excision was incomplete, and therefore this patient was addressed for further management.

The patient's case was discussed at our multidisciplinary meeting, and wide local excision was decided. The histological report of the re-excision revealed a lesion with a depth of 4 mm in the dermis reaching the limit of the hypodermis, with tumoral cells infiltrating the dermis and harboring nuclear atypia and high mitotic activity. The lesion was ulcerative with fibrinous leukocytic exudate. Vascular emboli were reported, and clear margins of 1 cm were achieved. Immunohistochemistry showed positive staining for carcinoembryonic antigen and cytokeratin (CK) 7 on the luminal ductal borders. p40 and CK5 and 6 were also positive on the whole cell population, and epithelial membrane antigen was heterogeneously positive. Those characteristics were consistent with the diagnosis of EPC. TNM classification was pT2.

Given the presence of vascular emboli, a staging CT scan of the thorax, abdomen, and pelvis was performed, which showed an image compatible with pelvic carcinomatosis. An additional FDG-PET scan was then requested, which displayed a hypermetabolic left inguinal lymph node and focal uptake in the right colon. Further investigations were conducted, which included a total colonoscopy and an inguinal left node biopsy. The ultrasound-guided node biopsy revealed distant infiltration of the porocarcinoma, whereas the endoscopy showed a large polyp that could not be endoscopically resected. Therefore, right colectomy combined with left inguinal and left iliac node dissection was performed, but the pathological findings showed no metastatic involvement. An additional ultrasound-guided resection was carried out to remove the targeted left hypermetabolic inguinal node, whose histology eventually revealed EPC and confirmed the disease's metastatic setting. The patient has been undergoing close follow-up for the last 4 months without any sign of relapse.