Intracytoplasmic Lipid Accumulation in Apocrine Carcinoma of the Breast Evaluated With Adipophilin Immunoreactivity

Abstract

Although apocrine carcinoma is a distinct histologic entity, there is no immunohistochemical marker to confirm apocrine differentiation with high sensitivity and specificity, and its differential cytologic characteristics are still not fully clarified. Despite the foamy cytoplasm of some apocrine carcinomas and the existence of lipid in the normal apocrine gland, intracytoplasmic lipid in apocrine carcinomas has not been fully explored. By using immunohistochemistry for adipophilin, which is a specific marker of lipid accumulation that can be applied to paraffin sections, we examined intracytoplasmic lipid in apocrine carcinomas. Twenty-four of 26 (92%) apocrine carcinomas and 38 of 116 (33%) nonapocrine carcinomas contained intracytoplasmic lipid. The frequency of adipophilin-positive cases was significantly higher in apocrine carcinomas compared with nonapocrine carcinomas (P<0.01). The positive cell rate per tumor ranged from 10% to 70% (mean, 29%) for apocrine carcinomas. The staining density was heterogeneous from cell to cell. There was no difference in the staining pattern of adipophilin between apocrine ductal carcinoma in situ and invasive apocrine carcinoma or between eosinophilic cells and foamy cells. Sporadic or mosaic distribution of adipophilin-positive cells throughout the tumor and microvesicular or fine granular cytoplasmic staining with heterogeneous density were characteristic features of apocrine carcinoma. Although intracytoplasmic lipid was identified in most apocrine carcinomas, none of the apocrine carcinomas contained prominent intracytoplasmic lipid in >90% of the tumor cells; thus, the criteria for lipid-rich carcinoma was not fulfilled. However, the immunohistochemical study suggests that lipid-rich carcinomas are closely related to apocrine carcinomas.

Adipophilin expression in cutaneous malignant melanoma

“…Moreover, many epithelioid melanomas with prominent nucleoli that presented with high ADP expression were associated with an abundant eosinophilic cytoplasm ( n = 15; 57.7%) (Fig. B), which was morphologically reminiscent of ADP‐positive carcinomas of the breast and lung . As discussed previously, there was no correlation between high ADP expression and histological subtype.…”

Lipid-rich carcinoma of the breast: A report of two cases and a literature review

“…As it is unclear as to the number of lipid-containing cells required to confirm the diagnosis of lipid-rich carcinoma, the definition of the tumor is not yet clearly established (3). Certain studies have suggested that >90% of the neoplastic cells should contain lipid droplets in lipid-rich carcinoma (2,7). The origin of the lipids in the neoplastic cells is also not clear.…”

Unusual Occurrence of Rare Lipid-Rich Carcinoma and Conventional Invasive Ductal Carcinoma in the One Breast: Case Report

“…The definition of lipid-rich carcinoma is still not exactly established, because it is not clear, how many cells are supposed to be lipid containing to confirm the diagnosis [6]. Some authors suggested that lipid-rich carcinoma should contain lipid droplets in more than 90% of the neoplastic cells [1, 7, 8]. Also the origin of the lipids in the neoplastic cells is matter of discussion.…”

“…None of the apocrine and nonapocrine carcinomas had positive staining of adipophilin in more than 90% of the cells, thus the criteria for lipid-rich carcinoma was not fulfilled. Their immunohistochemical study suggested that lipid-rich carcinomas and apocrine carcinomas are closely related [7]. …”