TUBULAR CARCINOMA OF THE BREAST - CYTOLOGIC FEATURES IN FINE-NEEDLE ASPIRATIONS AND APPLICATION OF MONOCLONAL ANTI-ALPHA-SMOOTH MUSCLE ACTIN IN DIAGNOSIS

Twenty fine-needle aspirations (FNAs) of histologically proven tubular carcinoma of the breast (TCB) were reviewed, and the staining distribution of alpha-smooth muscle actin (SMA) was evaluated to see if this improved FNA sensitivity. In 18 cases, the aspirates were cellular, consisting predominantly of epithelial cells arranged in cohesive tubular structures that appeared angular or twisted. Single epithelial cells were present in varying numbers in 14 cases (70%). Cribriform fragments corresponding to in situ ductal carcinoma were noted in 9 cases (45%). Individual, bare nuclei were present in seven cases (35%). The initial cytologic diagnoses were 10 carcinomas eight suspicious for carcinoma, and two cases were misinterpreted as fibroadenoma. In 8 of 14 cases, the epithelial fragments stained negatively for SMA, whereas in six cases some fragments (< 10%) stained positively. These findings were in contrast to a reticulated staining pattern noted in almost all of the epithelial fragments in nine fibroadenomas and three fibrocystic changes. Eighteen well-differentiated invasive ductal carcinomas stained negatively, whereas four had occasional positively staining fragments. We conclude that TCB displays distinct cytomorphologic features that can be recognized or at least suggested by FNA. Awareness of the cytologic characteristics-angulated tubular structures with or without single epithelial cells-coupled with mammographic/ultrasound findings, is necessary to avoid a misdiagnosis. Alpha-smooth muscle actin staining may help in selected cases. (C) 1994 Wiley-Liss, Inc.