Endocrine Mucin-Producing Sweat Gland Carcinoma and Primary Cutaneous Mucinous Carcinoma: A Case Series

Endocrine mucin-producing sweat gland carcinoma (EMPSGC) and primary cutaneous mucinous carcinoma (PCMC) are rare low-grade neoplasms thought to arise from apocrine glands. These neoplasms share many histologic features and are proposed to be on a single histopathologic continuum, with EMPSGC as the in situ form that may progress to the invasive PCMC,¹ which is analogous to ductal carcinoma in situ and mucinous carcinoma of the breast, respectively.^2-5 Management involves a metastatic workup and either wide local excision (WLE) with margins greater than 5 mm or Mohs micrographic surgery (MMS) in anatomically sensitive areas.² We present 2 cases of EMPSGC and 3 cases of PCMC. We also review the clinical and histopathological features, differential diagnoses, and treatments.

Methods

Following institutional review board approval, we conducted a retrospective, single-institution case series. We searched electronic medical records dating from 2000 to 2019 for tumors diagnosed as PCMC or extramammary Paget disease treated with MMS. We gathered demographic, clinical, pathologic, and follow-up information from the electronic medical records for each case (Tables 1 and 2). Two dermatopathologists (B.P. and B.F.K.) reviewed the hematoxylin and eosin–stained slides of each tumor as well as all available immunohistochemical stains. One of the reviewers (B.F.K.) is a board-certified dermatologist, dermatopathologist, and fellowship-trained Mohs surgeon.

Results

Demographic and Clinical Information—We identified 2 cases of EMPSGC and 3 cases of PCMC diagnosed and treated at our institution; 4 of these cases had been treated within the last 2 years. One had been treated 18 years prior; case information was limited due to planned institutional record destruction. Three of the patients were female and 2 were male. The mean age at presentation was 71 years (range, 62–87 years). None had experienced recurrence or metastases after a mean follow-up of 30 months.

Case 1—A 68-year-old woman noted a slow-growing, flesh-colored papule measuring 12×10 mm on the right lower eyelid. An excisional biopsy was completed with 2-mm clinical margins, and the defect was closed in a linear fashion. Histologic sections demonstrated EMPSGC with uninvolved margins. The patient desired no further intervention and was clinically followed. Magnetic resonance imaging (MRI) of the head and neck found no evidence of metastasis. She has had no recurrence after 15 months.

FIGURE 1. A flesh-colored papule on the left lower eyelid margin diagnosed as an endocrine mucin-producing sweat gland carcinoma (case 2).

Case 2—A 62-year-old man presented with a 7×5-mm, flesh-colored papule on the left lower eyelid margin (Figure 1). It was previously treated conservatively as a hordeolum but was biopsied after it failed to resolve with 3-mm margins. Histopathology demonstrated an EMPSGC (Figure 2). The lesion was treated with modified MMS with permanent en face section processing and cleared after 1 stage. Computed tomography of the head and neck showed no abnormalities. He has had no recurrence after 9 months.

FIGURE 2. Histopathology revealed a well-circumscribed papillary nodule without apparent mucin in the dermis, consistent with an endocrine mucin‐producing sweat gland carcinoma (case 2) (H&E, original magnification ×20).

Case 3—A 72-year-old man presented with a nontender papule near the right lateral canthus. A punch biopsy demonstrated PCMC. He was treated via modified MMS with permanent en face section processing. The tumor was cleared in 1 stage. He showed no evidence of recurrence after 112 months and died of unrelated causes. The rest of his clinical information was limited because of planned institutional destruction of records.

FIGURE 3. A painful pink, poorly circumscribed, subcutaneous nodule on the left lower abdomen diagnosed as a primary cutaneous mucinous carcinoma (case 4).

Case 4—An 87-year-old woman presented with a 25×25-mm, slow-growing mass of 12 months’ duration on the left lower abdomen (Figure 3). A biopsy demonstrated PCMC (Figure 4). Because of the size of the lesion, she underwent WLE with 20- to 30-mm margins by a general surgeon under general anesthesia. Positron emission tomography/computed tomography was unremarkable. She has remained disease free for 11 months.

FIGURE 4. Histopathology revealed basaloid tumors infiltrating the dermis surrounded by pools of mucin, consistent with a primary cutaneous mucinous carcinoma (case 4)(H&E, original magnification ×20).