Rosen's Breast Pathology, 4e

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Chapter 33

Occult breast carcinoma presenting as an ALNmetastasis is exceedingly unusual in men. 158–160 In some cases, axillary metastases from a nonmammary primary, such as carci­ noma of the lung, have been documented in men, generally after treatment of the pulmonary primary. 145,161,162 There is insufficient experience with this presentation of male breast carcinoma to compare with female patients. Gross Pathology The frequency with which a primary tumor is detected pathologically in the ipsilateral breast varies from 55% 133 to 82%. 130,138 In most series, the proportion with a documented primary was about 75%. 129,131,133,135,140 Although not clinically palpable, the majority of carcinomas were found upon gross examination of a mastectomy or excisional biopsy specimen (Fig. 33.10). Rarely, the breast has contained two separate, grossly evident invasive primary carcinomas, each of which may be accompanied by an in situ component. 135,152 The le­ sions have measured up to 6.5 cm, 130,134,135 but most were 1 to 2 cm or less in diameter. In one series, the median size was 1.9 cm and the mean 1.5 cm, with 82% classified as T1, 14% as T2, and 4% as T3 . 135 In a review of eight retrospective studies published in 2010, de Bresser et al. 149 reported that le­ sions detected by MRI measured between 5mm and 3cm and that the pathologically measured size of these lesions ranged from 1 mm to 5 cm. Smaller tumors were often discrete, with a stellate or circumscribed contour, but those larger than 2 cm more often had ill-defined margins and tended to blend grossly with the surrounding breast tissue. The majority of the primary lesions occur in the upper outer quadrant and less often in other quadrants. 131,133–135,137 The occult primary tumor has rarely been detected in the axillary tail. 151 About 30% of the clinically occult primary carcinomas are not evident when a mastectomy specimen is examined grossly. These lesions are found by taking multiple random

sections of breast tissue that appears grossly normal. Conse­ quently, sampling should not be limited to grossly abnormal parenchyma. Radiography of breast biopsies and mastecto­ mies has not been helpful for locating the primary and can­ not be relied upon for guidance in the sampling of tissue for histologic study. This is not unexpected in view of the lack of success with clinical mammography in these patients. The likelihood of finding a primary lesion in the breast is related to the thoroughness with which the available tissue has been studied. In some cases, the primary tumor remains undetected because a breast biopsy, or mastectomy, or both, was not performed. Despite careful and extensive gross and microscopic examination of a mastectomy, there are rare instances in which no primary is found. Patients not proven to have a primary breast carcinoma or a primary tumor at another site have a similar age distribution, similar lymph node findings, and comparable survival results as those with a pathologically demonstrated clinically occult breast carci­ noma. In one series, none of the 12 patients without a docu­ mented primary breast lesion were later shown to have an extramammary primary. 133 Axillary Lymph Nodes Among patients subjected to axillary dissection, the number of lymph nodes found to be involved by metastatic carci­ noma varies from one to as many as 65. 130,131,135,139 When nu­ merous lymph nodes are involved, they rarely form a matted mass with extranodal extension. In one series, one-half of the 40 patients had one to three involved lymph nodes (1 to 3 positive), including 13 patients whose only positive lymph node was the one removed for diagnosis (Fig. 33.11). Among 15 women with carcinoma, in four or more lymph nodes the median number involved was 11.

FIG. 33.11.  Occult carcinoma. This solitary enlarged ALN containing metastatic papillary carcinoma is greater than 2 cm in diameter. No primary tumor was detected in either breast by clinical palpation or on radiological evaluation. The metastatic carcinoma in the lymph node was ER ( + ), CK7 ( + ), CK20 (−), WT-1 ( + ), and PAX8 ( + ). A 3.0-cm ovar- ian papillary serous carcinoma was subsequently resected.

FIG. 33.10.  Occult carcinoma, mastectomy. The arrow indicates a small IDC that was not palpable clinically. A bisected ALN with metastatic carcinoma is shown in the lower right portion of the specimen.