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Adenoid cystic carcinoma of the breast (ACCB) is a rare triple negative tumor (TNT) with an excellent prognosis in most cases. Three different histologic types are recognized: classic ACCB, solid basaloid ACCB (SB-ACCB), and ACCB with high-grade transformation. A majority of these tumors show characteristic molecular and immunohistochemical (IHC) features, with fusion of MYB and NFIB genes and overexpression of MYB, respectively. Basaloid carcinomas of the breast (BCB) are infrequently described. They resemble SB-ACCB and TNT of no special type (TNT-NST). We have studied the clinicopathological features of 17 ACCB and 9 BCB, investigating the expression of MYB by IHC and the rearrangements of MYB by fluorescence in situ hybridization (FISH). MYB was expressed by IHC in 15 ACCB and in 3 BCB. MYB FISH detected rearrangements in 11 ACCB and in 2 BCB. After a mean follow-up of 90 months, with a range of 12-204 months, 2 patients with ACCB with high-grade transformation and 1 patient with BCB developed metastases and died of disease. In summary, most ACCB have a good prognosis, but tumors with adverse histopathological features may metastasize. BCB may overlap with ACCB and TNT-NST, and their prognosis should be further studied.

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Basaloid squamous cell carcinoma (BSCC) is a subtype of squamous cell carcinoma that characteristically occurs in the head and neck, may be related to HPV infection and is usually considered to be aggressive. We present the first description of BSCC of the breast. The tumor exhibited characteristic histologic features of BSCC, including nests of basaloid squamous cells with comedonecrosis, abrupt keratinization, and abundant hyaline basement membrane-like material deposition. The tumor showed immunohistochemical features of triple negativity, diffuse p63 positivity, p16 positivity, and Rb negativity. HPV immunogenotyping was negative. The patient was free of disease after treatment with breast conserving surgery, chemotherapy and radiotherapy. BSCC of the breast should be distinguished from basaloid adenoid cystic carcinoma, triple-negative basal-like breast cancer and nonbasaloid squamous cell carcinoma of the breast based on histology and immunohistochemistry. The prognostic implications of BSCC of the breast should be further studied in larger series.

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The objective of this case report was to describe histopathological and immunohistochemical characteristics of the first reported basaloid carcinomas in the canine mammary gland. Two bitches were treated for tumors in the mammary gland and underwent mastectomy. Microscopic evaluation of these tumors revealed epithelial cells arranged in a predominantly solid pattern with hyperchromatic peripheral cells arranged in a palisade pattern. Metastases in regional lymph nodes were found in both animals, and one bitch exhibited pulmonary metastasis. Immunohistochemistry revealed positive labeling for the basal cell markers cytokeratin 14 and p63. Histopathological and immunohistochemical findings led to diagnoses of basaloid carcinoma of the canine mammary gland with regional and distant metastasis.(AU)

O objetivo deste relato de caso é descrever as características histopatológicas e imuno-histoquímicas do primeiro relato de carcinoma basaloide na glândula mamária canina. Duas cadelas foram atendidas com tumores na glândula mamária e foram submetidas à mastectomia. A avaliação microscópica demonstrou células epiteliais arranjadas em um padrão predominantemente sólido, com células periféricas hipercromáticas, dispostas em paliçada. As duas apresentaram metástase em linfonodos regionais e uma delas metástase pulmonar. A imuno-histoquímica revelou marcação positiva para citoqueratina 14 e p63, marcadores de células basais. Achados histopatológicos e imuno-histoquímicos levaram ao diagnóstico de carcinoma basaloide da glândula mamária canina com metástase regional e a distância.(AU)

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