Fine-Needle Aspiration of Low-Grade Adenosquamous Carcinomas of the Breast: A Report of Three New Cases

Abstract

Objectives: To describe cytology patterns in low-grade adenosquamous carcinomas (LGASCs) of the breast. Study Design: Low-grade adenosquamous carcinomas of the breast are a recently described rare variant of primary metaplastic carcinomas characterized by clinical indolence, slow evolution and excellent survival. To date, only 7 cases of LGASC were studied cytologically, and it was demonstrated that LGASC identification was difficult because its cellular components exhibited unspecific and nonsuspicious features. They consisted of irregularly clustered cells without prominent cytonuclear atypia, mitosis or necrosis. The presence of metaplastic cells or keratin debris was helpful in accurate tumor typing. We report here 3 additional cases of LGASC that were initially studied by fine-needle aspiration. Results: We have also encountered diagnostic difficulties and misdiagnosed tumors, since 2 cases were underdiagnosed as ‘suspicious' and only 1 was accurately diagnosed as malignancy. Conclusion: The review of our cases and the literature confirms that, despite its putative metaplastic origin, LGASC is an entity which is difficult to diagnose using classical cytological methods. Moreover, core-needle biopsy as well as frozen sections may also misdiagnose LGASC as a benign breast lesion.

Bilateral synchronous low-grade adenosquamous carcinoma of the breast: A Case report with review of the current literature

“…2 & 4 ). Both LGASC and SAN are positive for CK5/6 and p63 [10] , and negative for ER, PR, and HER2 [5,21] . Boecker et al showed LGASC and SAN contain p63+/K5/K14+ tumor cells, K10+ squamous, and K8/18+ glandular cells.…”

“…Accurate diagnosis of LGASC preoperatively is often impossible at fine-needle aspiration cytology (FNAC) due to a paucity of classical cytological features of malignancy [5,11,14–16] . 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.…”

“…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] . Immuno-markers 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] .…”

“…Traditionally, LGASC and SAN have been regarded as separate entities; accurate distinction remains a considerable challenge as seen in the primary excision sample of the left breast in our case. Reports in the literature have mislabeled these lesions [5,19] , with some authors currently using the terms ‘LGASC’ and ‘infiltrating syringomatous adenoma’ synonymously [1,13,14] . Both lesions are locally aggressive with a propensity for local recurrence.…”

“…A total of 18 manuscripts (1987 to present) describing 109 cases of LGASC are summarized in Table 1 [1–18] . Patients’ ages range from 19 to 88, with two cases of bilateral LGASC being reported.…”