Break a Sweat in the Diagnosis and Management of a Flesh‐Colored Nodule

Abstract

Eccrine porocarcinoma (EPC), which is a tumor of the sweat ducts, most commonly affects older adults, with an average age of 68, but may occur at any age.1 It may arise originally in malignant form2 but most often develops from a long-standing benign eccrine poroma as a form of degenerative progression.3 It is not uncommon for the lesion to be misdiagnosed. Because the tumor has the capacity to metastasize, with consequent poor prognosis, it is imperative for accurate diagnosis and management. A 63-year-old man presented with a 4-month history of a flesh-colored nodule over the left upper cutaneous lip that had been enlarging gradually and was asymptomatic. There had been no preexisting lesion at the site before onset. His past medical history included hypertension for which he was taking antihypertensives. Clinical examination revealed a flesh-colored 15- × 10-mm nodule over the left upper cutaneous lip extending to the vermillion. There was telangiectasia over the surface. There was no pearly margin (Figure 1). A punch biopsy was performed that revealed a dermal-based tumor with nests of tumor cells with ductal structures showing numerous mitotic figures at low magnification. Polyclonal carcinoembryonic antigen (CEA) highlighted ducts, confirming their eccrine differentiation. A diagnosis of EPC was made, and the lesion was excised in one stage with two blocks using Mohs micrographic surgery (MMS) and the defect closed with mucosal advancement of the lip. EPC has a propensity to arise on the lower limbs (44%), trunk (24%), or head and neck (24%).4-6 One problem with EPC is delay in definitive treatment because of the tumor's indolent behavior or misleading clinical diagnosis.7 The tumor is typically formed of cohesive basaloid epithelial cells and may be misdiagnosed as basal cell carcinoma. Foci of squamous differentiation that can resemble well-differentiated squamous cell carcinoma are often observed within EPC. The presence of ductal structures and use of immunostains help in making the histological diagnosis. Regional lymph node metastases are found in approximately 20% of patients, and distant metastases arise in approximately 10% of patients. There is an approximately 67% mortality in individuals with lymph node metastases.8 Its metastatic potential and poor outlook in the event of metastasis dictates the need for early identification and complete excision as the best chance of a cure. EPC has been treated using a variety of methods, including electrosurgery, simple and wide excision, MMS, and radiation. Curative rates of 70% to 80% have been reported for excision, with recurrence rates as high as 20% being reported.1, 5 Recurrences had been reported to occur 4 months to 12 years after treatment.9 One study7 reported that three of eight individuals had recurrences after wide excision (≥10-mm margins). Thus simple or wide excision is not the optimal treatment for EPC. MMS appears most promising. Another study10 reported a series of five cases of primary EPC treated using MMS without recurrence after 2 to 4 years of follow-up. The current patient was treated using MMS. Tumor extirpation was achieved in one stage with two blocks. One year after treatment, no recurrence was noted. primary and metastatic EPC have shown poor response to radiation therapy. Chemotherapy also has a poor response and is generally reserved for treatment of documented metastatic EPC. EPC is challenging for surgeons and medical and radiation oncologists. Because of its rarity and lack of consensus and guidelines for its management, EPC is a challenge to treat. MMS, which allows for full evaluation of the tumor margins, may be the ideal treatment for this rare tumor. Because tumor recurrence had been reported 12 years after treatment, monitoring is essential after treatment. Conflict of Interest: The editor in chief has reviewed the conflict of interest checklist provided by the authors and has determined that the authors have no financial or any other kind of personal conflicts with this paper. Author Contributions: Both authors were involved in the analysis and interpretation of data and preparation of manuscript. Sponsor's Role: None.