Independent primary cutaneous and mammary apocrine carcinomas with neuroendocrine differentiation: Report of a case and literature review

Abstract

Cutaneous apocrine carcinomas share common features with their counterparts in the breast; hence, metastatic mammary carcinoma must be excluded before such lesions can be designated primary cutaneous neoplasms. Primary tumors from either source rarely exhibit neuroendocrine differentiation. We report a case of a 72-yearold female with a painless 1.2-cm scalp nodule. An incisional biopsy revealed dermal involvement by an invasive apocrine carcinoma juxtaposed to a benign apocrine cystic lesion. Immunohistochemically, the carcinoma expressed neuroendocrine proteins including synaptophysin, chromogranin, and CD56. A primary cutaneous apocrine carcinoma with neuroendocrine differentiation was favored, but additional investigations to exclude breast origin were recommended. These revealed a 1.1-cm nodule in the right breast, which proved to be an invasive ductal carcinoma, morphologically and immunophenotypically similar to the scalp lesion. This confounded the case, yet factors militating against metastatic breast carcinoma to skin included (a) the small size of the mammary tumor, (b) absence of other metastatic disease, and (c) juxtaposition of the scalp carcinoma to a putative benign precursor. Molecular studies were undertaken to resolve the diagnostic quandary. Single nucleotide polymorphism microarray analysis revealed distinct patterns of chromosomal copy number alterations in the two tumors, supporting the concept of synchronous and unusual primary neoplasms.

Primary cutaneous apocrine carcinoma of the scalp

“…On the contrary, metastatic breast adenocarcinoma is often positive for ER and PR [13] . There have been reports that mammaglobin yields better staining in PCAC than in breast adenocarcinoma, and that these 2 tumors can be distinguished based on molecular studies [14,15] . In the reported cases, the probability of metastasis from a primary breast lesion was low as all the patients were men and the tumors were negative for ER and PR.…”

“…based on molecular studies. [14,15] In the reported cases, the probability of metastasis from a primary breast lesion was low as all the patients were men and the tumors were negative for ER and PR. The standard treatment for apocrine carcinoma is surgical excision with or without lymph node dissection.…”

“…In total, 36 cases had detailed reports that were gathered and condensed in Table 1. [1,3,4,[7][8][9][10][11][12]14,[19][20][21][22][23][24][25][26][27][28][29][30][31][32][33] Of the 36 cases obtained, 16 were in female patients and 20 were in male patients. The average age at the time of diagnosis was 60.8 years and it ranged from 20 to 85 years.…”

“…In total, 36 cases had detailed reports that were gathered and condensed in Table 1 [1,3,4,7–12,14,19–33] . Of the 36 cases obtained, 16 were in female patients and 20 were in male patients.…”

Prognostic factors in cutaneous apocrine carcinoma: a single-institution retrospective study of 32 patients

“…Owing to the lack of characteristic clinical ndings, the CAC cannot be detected until the tumor grows. Therefore, CAC is often misdiagnosed as a metastatic adenocarcinoma or cannot be de nitively diagnosed [9,14]. Since CAC is a primary cutaneous carcinoma, adenocarcinoma of other organs such as breast cancer should be excluded to make a diagnosis of CAC [14].…”