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 distrib ution of alpha-smooth muscle actin (SMA) was evaluated to see if this improved FNA sensitivity. In 18 cases, the aspirates were cellular, co nsisting predominantly of epithelial cells arranged in cohesive tubula r structures that appeared angular or twisted. Single epithelial cells were present in varying numbers in 14 cases (70%). Cribriform fragmen ts corresponding to in situ ductal carcinoma were noted in 9 cases (45 %). Individual, bare nuclei were present in seven cases (35%). The ini tial cytologic diagnoses were 10 carcinomas eight suspicious for carci noma, and two cases were misinterpreted as fibroadenoma. In 8 of 14 ca ses, the epithelial fragments stained negatively for SMA, whereas in s ix cases some fragments (< 10%) stained positively. These findings wer e 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 stain ed negatively, whereas four had occasional positively staining fragmen ts. We conclude that TCB displays distinct cytomorphologic features th at can be recognized or at least suggested by FNA. Awareness of the cy tologic characteristics-angulated tubular structures with or without s ingle epithelial cells-coupled with mammographic/ultrasound findings, is necessary to avoid a misdiagnosis. Alpha-smooth muscle actin staini ng may help in selected cases. (C) 1994 Wiley-Liss, Inc.