Carcinoma microinvasivo de mama: estudio clinicopatológico de 18 casos Microinvasive breast carcinoma: a clinicopathological profile of 18 cases

SUMMARY Introduction: The exact definition of microinvasive breast carcinoma remains problematic, and its clinical beha- vior is uncertain. We have studied retrospectively 38 cases with the diagnosis of microinvasive carcinoma made in dif- ferent institutions, according to the criteria of Silver and Tavassoli. Material and Methods: We describe the clinico- pathologic characteristics and the reproducibility of the diagnosis of microinvasion, following predetermined crite- ria. We also study the value of immunohistochemical stains with p63 and calponin, to establish the integrity of the myo- epithelial layer. Results: The cases were reviewed by two of the authors (FG, VM) and reclassified as microinvasive car- cinoma, 18 cases (47%), doubtful microinvasion, 1 case, ductal carcinoma in situ (DCIS) with pseudoinvasion, 11 cases (28.9%), and invasive ductal carcinoma pT1a and pT1b, 8 cases (21.6%).The size of the associated DCIS varied between 7 and 80 mms. In eleven cases one single focus of microinvasion was found, the other cases showed two or three foci of microinvasion. Two cases showed angiolymphatic invasion, as the only evidence of microinva- sion. Immunohistochemistry with calponin and p63 was helpful in the diagnosis of microinvasion in 50% of the cases. Axillary lymph nodes were obtained in 15 cases, and a single positive lymph node was found. One patient recu- rred as DCIS in the surgical scar nine months after surgery. The other patients were disease free after a variable follow- up, between 3 and 120 months (average 42 months). Con- clusions: Microinvasive breast carcinoma is often overdiag- nosed histologically. The implementation of strict morpho- logical criteria and the use of immunohistochemistry may be helpful in the differential diagnosis with DCIS and inva-