[142] Extramammary Metastases to the Breast and Axilla: A Study of 78 Cases.

Deborah DeLair, Adriana D Corben, Jeffrey Catalano, Edi Brogi, Christina Vallejo, Lee K Tan. Memorial Sloan-Kettering Cancer Center, New York, NY

Background: Breast and axillary metastases from extramammary malignancies (EM) are rare but their recognition is critical as treatment and prognosis differ from those of breast carcinoma (BC). We sought to assess clinical and pathologic features of EM to the breast and axilla.
Design: A search of the 1990-2010 pathology database identified patients (pts) with EM involving the breast and/or axilla. The clinical and pathologic features were reviewed.
Results: A total of 78 pts had EM involving the breast (78%), axilla (6%), or both (16%). Tumor types, primary sites, and clinical features are summarized in Tables 1 & 2. The most frequent EM was carcinoma (56%), with ovarian high grade serous (HGS) being the most common. Melanoma (23%) and a wide variety of sarcomas (21%) were the next most frequent. The majority of pts had advanced disease (78%) when the breast/axillary lesion developed. In 13% of cases, an initial diagnosis of primary BC was rendered, HGS being the most frequently misdiagnosed. Pathologic features common among metastases included formation of a well-circumscribed nodule surrounded by a fibrous capsule and absence of in situ carcinoma. In contrast to other organs in which multiple metastatic lesions are frequent, the majority of metastases to the breast formed a solitary lesion.

Table 1: Tumor types and primary sites (n=78)
Carcinoman=44 (56%)
Ovary12/44 (27%)
Lung10/44 (23%)
GI tract6/44 (13%)
GYN tract (excluding ovary)4/44 (9%)
GU tract4/44 (9%)
Thyroid3/44 (7%)
Merkel Cell3/44 (7%)
Others2/44 (5%)
Melanoman=18 (23%)
Sarcoman=16 (21%)
Uterine leiomyosarcoma5/16 (31%)
Rhabdomyosarcoma3/16 (19%)
Liposarcoma2/16 (13%)
Others6/16 (37%)

Table 2: Clinical features (n=78)
Median age54 yr (range 15-83)
Female/male85%/15% (66/12)
Median size1.68 cm (range 0.05-18 cm)
Unilateral/bilateral88%/12% (69/9)
Solitary mass71% (59)
Other metastases at diagnosis78% (61)
Initially diagnosed as primary breast carcinoma13% (10) (high grade serous 6/10, 60%)
Interval from primary to breast metastasis4.5 yr (range synchronous-16 yr)

Conclusions: A wide range of primary sites can metastasize to breast and axilla and although a rare occurrence, a significant portion of these tumors may be misdiagnosed as primary BC. The importance of a complete clinical history is emphasized as the majority of patients had advanced disease upon development of the breast/axillary lesion. In addition, pathologists should be aware of certain histologic features commonly seen in EM to the breast/axilla in order to avoid unnecessary treatment and/or procedures.
Category: Breast

Tuesday, March 1, 2011 1:00 PM

Platform Session: Section B, Tuesday Afternoon


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