The epithelial component of normal and noninvasive breast tumor tissue is physically separated from the stroma by both the myoepithelial cells and the basement membrane (BM). Myoepithelial cells are joined by intermediate or gap junctions and a number of intercellular adhesion molecules, forming a continuous sheet or belt that encircles the epithelial cells (except at the terminal ductal-lobular unit, within which about 20% of the epithelial cells are reported to be in direct contact with the BM) BM = basement membrane; DCIS = ductal carcinoma in situ; ER = estrogen receptor; H & E = hematoxylin and eosin; LOH = loss of heterozygosity; MI = microsatellite instability; PCR = polymerase chain reaction; SMA = smooth muscle actin. AbstractIntroduction Our previous studies detected focal disruptions in myoepithelial cell layers of several ducts with carcinoma in situ. The cell cluster overlying each of the myoepithelial disruptions showed a marked reduction in or a total loss of immunoreactivity for the estrogen receptor (ER). This is in contrast to the adjacent cells within the same duct, which were strongly immunoreactive for the ER. The current study attempts to confirm and expand previous observations on a larger scale.

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Changes in CNRs of relatively high- and low-frequency US images may give useful information on the frequency dependence of backscattering, which is descriptive of the histologic findings in lesions and which is not evident with conventional US images.

Calcifying aponeurotic fibroma is a rare benign soft tissue proliferation, which occurs in the distal extremities in children. We describe a case of calcifying aponeurotic fibroma of the hand in a 9 year-old male diagnosed by FNA. Clinically and radiographically this mass was felt to be suspicious for sarcoma, likely alveolar rhabdomyosarcoma. Cytologic examination revealed benign appearing spindled cells, chondroid cells, multinucleated giant cells and calcific debris. These features recapitulate the classic histologic features of calcifying aponeurotic fibroma. Conservative excision was performed and histologic exam confirmed the diagnosis. To the authors' knowledge, this is the first description of the cytologic features of this entity.

Tubulolobular carcinoma (TLC) is a rare subtype of mammary carcinoma that has eluded precise classification, exhibiting features of both ductal and lobular differentiation. The clinicopathologic features of 27 cases of TLC were analyzed by both hematoxylin and eosin and immunohistochemical stains for E-cadherin and 34betaE12 (high molecular weight cytokeratin). Five cases of both pure tubular and classic lobular carcinoma were included as controls. Patients with TLC ranged in age from 43 to 79 years (median, 60 years). Tumor characteristics were as follows: size, 0.5 cm to 2.5 cm (median, 1.4 cm); bilaterality, 1 of 27 (4%); and multifocality, 5 of 27 (19%). Twenty-two of the 27 cases (81%) contained an in situ component: 8 (36%) lobular (LIN); 4 (18%) ductal (DIN); and 10 (46%) mixed. All 27 cases were intensely positive (3+) for E-cadherin, a feature of ductal differentiation, while 25 of 27 (93%) cases showed variable positivity for 34betaE12 (1 to 3+), a feature far more common in tumors with lobular differentiation. Clinical follow-up was available on 25 of 27 (93%) patients. Three of 24 (13%) patients developed axillary lymph node metastases and 1 of 25 (4%) patients developed a local recurrence over a follow-up period of 2 to 91 months (median, 39 months). In conclusion, TLCs are a distinct subtype of mammary carcinoma with overlapping morphologic features that are mirrored by a hybrid immunohistochemical profile. The uniform 3+ expression of E-cadherin in TLC supports the ductal differentiation of these tumors, despite a dominant lobular growth pattern. The prognosis of these tumors appears to be excellent, especially in those cases that are unilateral and less than 2 cm in size.