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INVASIVE APOCRINE CARCINOMA |
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INVASIVE APOCRINE CARCINOMA |
| Although many invasive breast cancers of various types show some evidence
of apocrine differentiation, fewer than 1% of invasive breast carcinomas demonstrate pure
apocrine features (i.e., exhibit cytologic characteristics that resemble those of apocrine
sweat glands). Although the morphologic features of these tumors are distinctive,
available evidence suggests that patients with these tumors have the same prognosis as
patients with invasive breast cancers of no special type. Clinical Presentation Patients with apocrine carcinomas are similar in age and mode of presentation to patients with invasive carcinoma of no special type. As an exception, one study reported that 7 of 34 patients (21%) demonstrated skin involvement by tumor. Only rare examples of apocrine carcinoma have been reported in males. A low incidence of multifocal lesions and contralateral tumors is reported. The mammographic characteristics of apocrine carcinomas are not distinctive. Most tumors present as masses with ill-defined margins, and microcalcifications are infrequent.In addition, the ultrasonographic findings associated with these tumors are nonspecific. Gross Pathology No distinctive gross findings are associated with apocrine carcinoma, and the size distribution is similar to that of invasive carcinomas of no special type. Histopathology The histologic features of apocrine carcinoma, in contrast, are highly distinctive. The invasive patterns are usually those seen in invasive ductal carcinoma, but in some cases, lesions with apocrine cytology can exhibit a pattern of invasion more characteristic of invasive lobular carcinomas. One variant with a distinctive dyshesive and diffusely infiltrative pattern has been designated as having “myoblastoid” or “histiocytoid” features,and in some cases, this lesion may mimic a granular cell tumor. Cytologically, the tumor cells have cytoplasm that is abundant and eosinophilic, with obvious granularity in some cases. The nuclei vary in grade, but typically show prominent nucleoli . DCIS is frequently associated and may have apocrine features. Extensive lymphatic vessel invasion, including dermal lymphatic involvement, was identified in 4 of 34 cases (12%) in one study. Apocrine carcinomas characteristically
show immunostaining for gross cystic disease fluid protein.75 Five of 18 apocrine
carcinomas (28%) described in three studies were positive for estrogen receptors. DNA
studies using Feulgen-stained tissue sections demonstrated that 14 of 17 apocrine
carcinomas were aneuploid, and the remainder were diploid. These data may be skewed,
however, because all but two of the tumors analyzed were high grade. In addition, only 1
of 5 apocrine carcinomas (20%) exhibited p53 protein accumulation by immunohistochemistry. |
