Porocarcinoma: an exceedingly rare tumor or a tumor eclipse phenomenon?

Porocarcinoma: an epidemiological, clinical, and dermoscopic 20-year study

BACKGROUND

Porocarcinoma (PC) is a rare cutaneous adnexal tumor with a variable metastatic potential. Given the paucity of data, guidelines and specific recommendations for PC are not yet well-established. In this study, we evaluate the disease-specific characteristics and outcome of this rare and often underestimated tumor.

MATERIALS AND METHOD

A retrospective study of the epidemiological, clinical, and dermoscopic characteristics among cases of histopathologically diagnosed PC, collected from the database of two skin cancer clinics in Italy (Firenze, Pistoia) from 2000 to 2020, was conducted.

RESULTS

Among the 52 patients with 53 tumors, 31 were men (59.6%) and 21 were women (40.4%) with an age range of 49-96 years (median age 82 years). The most common locations were the head/neck region in men (34% in men vs. 17% in women) and the lower limb in women (17% in women vs. 9% in men). Forty-eight cases (91%) underwent local excision. Of these patients, two (4%) experienced local recurrence, and one (2%) developed a second PC on a different anatomical site 1 month after the primary tumor's excision. Lymph node metastases were present in three cases (6%). Two of them have been treated surgically with adjuvant radiotherapy (both are disease-free after a 2-year follow-up period), whereas the third case developed visceral metastases followed by PC-related death.

CONCLUSIONS

This study, with 52 patients with 53 tumors covering a follow-up period of more than 5 years, shows a less aggressive behavior of PC with 4% local recurrence, 6% nodal metastases, and 2% mortality.

Engrailed Homeobox 1 and Cytokeratin 19 Are Independent Diagnostic Markers of Eccrine Porocarcinoma and Distinguish It From Squamous Cell Carcinoma

OBJECTIVES

The diagnostic utility of En1 in the histopathologic differentiation of eccrine porocarcinoma (EPC) from invasive squamous cell carcinoma (SCC) was investigated.

METHODS

Expression of En1 and CK19 in 16 cases of EPC was immunohistochemically examined and compared with that in 32 cases of SCC.

RESULTS

In all 16 EPCs, En1 was expressed in 3% to 100% of tumor cells. In 20 of the 32 SCCs, En1 was expressed in 3% to 90% of tumor cells. A total of 13 of the 16 EPCs and five of the 32 SCCs were judged as En1 positive, with a cutoff value of 25%. In addition, 11 of the 16 EPCs and four of the 32 SCCs were CK19 positive. The frequencies of En1- and CK19-positive cases were significantly higher in EPCs than in SCCs. In a logistic regression analysis for predicting EPC, En1 and CK19 were independent markers. When expression patterns of En1 and CK19 were combined, none of the 32 SCCs was both positive. In contrast, 15 of the 16 EPCs were positive for either En1 or CK19.

CONCLUSIONS

A combination of En1 and CK19 expression can improve the accuracy of histologic diagnosis of EPC.

Porocarcinoma with areas of mucinous differentiation suggesting multilineage differentiation

Porocarcinoma is an infrequent malignant adnexal carcinoma, with some histopathological variants described, such as the clear cell, the sarcomatoid or the pigmented porocarcinoma. We report an invasive porocarcinoma showing areas of tumor cells floating in prominent dermal mucin, simulating mucinous carcinoma, that we consider a new histopathological variant of porocarcinoma. We report a 74-year-old male with previous history of multiple basal cell carcinomas that presented a nodule on his left temple. Histopathologic study showed a large ulcerated multilobular tumor composed of thickened cords of cells emanating from a hyperplastic epidermis and showing a mixed infiltrative and pushing pattern in the dermis. Poroid differentiation was observed in most of the neoplasm, both in intraepidermal and dermal invasive component. Within the neoplasm a prominent area where these small nests with clear formation of ducts were floating in mucinous pools with few septa intermingled was observed, simulating a primary cutaneous mucinous carcinoma. Cytology, immunohistochemistry and the presence of both neoplastic areas as closely related and with multiple points of connectivity favors the consideration of a composite tumor in this peculiar case. Other differentials are discussed.

Eosinophilic variant of eccrine porocarcinoma of the scalp: Case report and review of the literature

Porocarcinoma is a rare malignant neoplasm of the acrosyringium with metastatic potential that most commonly presents on the acral skin in older adults (mean age = 72 years). We present the case of a 43-year-old woman who developed a rapidly growing de novo porocarcinoma on the scalp with an unusual oncocytic appearance. The tumor consisted of benign eccrine poroma that arose from the epidermis and broad pushing borders with minimal cytological atypia but ample eosinophilic cytoplasm with numerous mitotic figures. Although some tumors may appear deceptively bland, the histologic recognition of pushing/infiltrative borders and mitotic figures are helpful to make the appropriate diagnosis of carcinoma. This lesion was treated with Mohs micrographic surgery and the patient remained free of recurrence after more than 2 years. It is important to recognize the eosinophilic variants of eccrine porocarcinoma because it can histologically mimic a squamous cell carcinoma.

Cytodiagnosis of Eccrine Porocarcinoma of the Scalp

Eccrine porocarcinoma is a rare, malignant adnexal tumor of the duct of eccrine sweat gland. Cytology of eccrine porocarcinoma has been described in very few previous literature. Here, we present a case of fine needle aspiration cytology (FNAC) of eccrine porocarcinoma of the scalp, which is subsequently confirmed by histology. Accurate diagnosis of eccrine porocarcinoma by FNAC is very difficult, but determining the malignant nature of the lesion is crucial for curative surgery. FNAC can be a convenient, safe, and effective approach to solve difficult diagnostic dilemma.

Treatment of eccrine porocarcinoma with Mohs micrographic surgery: a cases series and literature review

BACKGROUND

Eccrine porocarcinoma (EPC) is a rare malignant tumor of the eccrine sweat gland. It is a potentially fatal neoplasm that is locally aggressive and commonly recurs. Wide surgical excision has traditionally been the treatment of choice and is curative in approximately 70-80% of cases. The disease is metastatic to lymph nodes and distant sites in 20% and 10% of cases, respectively. Metastatic EPC has not shown any great response to adjuvant chemotherapy or radiation.

OBJECTIVE

The purpose of this study was to evaluate the efficacy of Mohs micrographic surgery (MMS) for EPC as an alternative to wide local excision.

METHODS

Five patients diagnosed with EPS between 2011 and 2014 at the University of Louisville and treated with MMS were studied. Recurrence-free periods subsequent to the treatment of EPC with MMS were measured.

RESULTS

The five patients with EPC treated by MMS remained recurrence-free for a mean of 11 months (range: 2-26 months).

CONCLUSIONS

Mohs micrographic surgery is a highly effective treatment for EPC. Given the high rate of recurrence, propensity for lymph node metastases, and the often ineffective options for treating advanced disease, MMS should be considered in the treatment of all cases of EPC.

[Eccrine porocarcinoma with Bowenoid changes: a challenging diagnosis of adnexal neoplasm]

Eccrine porocarcinoma is a rare malignant sweat gland tumor, representing less than 0.01% of all cutaneous neoplasms, with eccrin differentiation. Its acrosynringeal origin and physiopathology still remain discussed. The prognosis of this carcinoma is held to be poor with a significant risk of lymph node metastasis and local recurrence. Also, this not specific tumor can be a challenging histological diagnosis, in particular, in Bowenoid variant. We report a case of Bowenoid and keratinizing variant of eccrine porocarcinoma of the left ring finger with pejorative evolution and initial diagnosis of infiltrating squamous cell carcinoma arising in Bowen's disease. The knowledge of these patterns and identification of eccrine differentiation of the tumor are essential for the diagnosis and for adapted therapeutic care.