Preoperative and intraoperative diagnosis of low-grade adenosquamous carcinoma of the breast: Potential diagnostic pitfalls

Department of Pathology, Singapore General Hospital, Singapore.
Histopathology (Impact Factor: 3.45). 01/2007; 49(6):603-11. DOI: 10.1111/j.1365-2559.2006.02524.x
Source: PubMed


Low-grade adenosquamous carcinoma (LGAC), a rare variant of metaplastic breast cancer, may mimic benign or other low-grade malignant lesions histologically. Diagnostic difficulty may be encountered when evaluating breast cytology, core needle biopsy or intraoperative frozen section specimens.
Pathology reports, cytology aspirates and histological slides of LGAC diagnosed at the Department of Pathology, Singapore General Hospital, were reviewed. Four cases of LGAC were analysed. Cytology from the first case showed atypical cells and the subsequent surgical excision specimen showed a complex sclerosing lesion with LGAC. The second and third cases were investigated by core needle biopsies: the preoperative histological features were suggestive of but not diagnostic of LGAC, until further excision biopsies were performed. The fourth case entailed a frozen section specimen, for which definitive diagnosis was deferred to paraffins. The patients remained well with no evidence of recurrent disease to date.
When limited material, in the form of needle aspirates, core biopsy specimens or frozen sections, is submitted for histology, making a diagnosis of LGAC is not only challenging, but may be impossible. In difficult cases, careful pathological assessment, clinicopathological correlation and follow-up or complete excision biopsy may prove invaluable in establishing a definitive diagnosis.

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    • "At core biopsy the overall architecture is not appreciable, and intraoperative frozen section is limited due to sampling [13] [19]; therefore, preoperative confirmation is rare, as seen in the biopsy from the left breast in our case. Nuclear uniformity/enlargement, monomorphism , keratin debris, and the presence of metaplastic squamous cells may reduce false negative rates on FNAC [5] [13]. Immunomarkers such as p63 may aid in recognizing the squamous elements that facilitate exact tumor typing; however, this requires a high preoperative index of suspicion [12]. "
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    ABSTRACT: Low-grade adenosquamous carcinoma (LGASC) is a rare, unique variant of metaplastic breast carcinoma, characterized by clinical indolence and low-grade cytomorphology. Being clinically asymptomatic with indefinite imaging characteristics, diagnosis is solely dependent on histopathology. A 68-year-old woman presented to the Breast Health Center with mammogram-detected left-sided retroareolar calcifications. She had a three-year history of non-progressive bilateral nipple inversion, and was otherwise asymptomatic. Left breast biopsy revealed atypical metaplastic squamous epithelial cells. Subsequently a wire-guided lumpectomy diagnosed a syringomatous adenoma of the nipple. A surveillance MRI identified a contralateral breast lesion, which on core biopsy showed an atypical adenosquamous lesion. Bilateral central mastectomies with bilateral sentinel node biopsies were undertaken. Histopathological review of both breast specimens confirmed the unique features of adenosquamous carcinoma identified by an infiltrative pattern of small rounded compressed angulated glands with squamous differentiation and low-grade cytomorphology. The tumors were triple negative [ER, PR, HER2]. The sentinel lymph nodes were negative. Bilateral synchronous LGASC of the breasts is exceedingly uncommon and remains a diagnostic and therapeutic challenge. Despite being triple negative, due to its indolent behavior, recognition of this unusual primary breast malignancy is important as it has a more favorable prognosis. Yet, due to its rarity, there are no guidelines for best practice management regarding the role of adjuvant therapy. Copyright © 2015 The Authors. Published by Elsevier Ltd.. All rights reserved.
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    • "Apesar da alta incidência de tumores de mama em mulheres , o tipo histológico de carcinoma adenoescamoso é raro. O carcinoma adenoescamoso de mama em geral é caracterizado por ser bem circunscrito, integrante do grupo dos carcinomas metaplásicos, associados à mutação do antioncogene BRCA1 e ao bom prognóstico (Ho et al 2006, Geyer et al. 2010, Noël et al. 2010). Independente do tipo histológico, tanto em mulheres como em outros animais como cadelas, gatas e possivelmente em primatas não humanos , o tratamento para as neoplasias malignas de mama deve ser realizado de forma precoce para a obtenção de melhor prognóstico (Gomes 1997, Lana et al. 2007, Morris & Dobson 2007). "
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    • "However, due to the inherent limitations of the core biopsy, diagnostic excision was recommended by the histopathologist. Ho et al [4] have demonstrated in their small series of four cases that limited material in fine needle aspiration/core biopsy does not yield enough material for confirmatory histopathological diagnosis. "
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