Cannatella John, Ganapathi Karthik, Horvai Andrew
From the Department of Pathology (Cannatella, Horvai), University of California, San Francisco, San Francisco.
Cannatella is now with the Department of Pathology, University of Arkansas for Medical Sciences, Little Rock.
Arch Pathol Lab Med. 2020 Dec 1;144(12):1547-1552. doi: 10.5858/arpa.2019-0580-OA.
CONTEXT.—: Undifferentiated pleomorphic sarcoma (UPS) of soft tissue is defined as a sarcoma with no recognizable line of differentiation. During the past few decades, advances in ancillary studies and review of prior UPS diagnoses have narrowed the category of UPS by excluding more-specific malignancies. However, few of those studies have specifically targeted pleomorphic hematolymphoid neoplasms.
OBJECTIVE.—: To determine what fraction of UPS cases are misclassified pleomorphic hematolymphoid neoplasms, such as anaplastic large cell lymphoma, diffuse large B-cell lymphoma, histiocytic sarcoma (HS), myeloid sarcoma, and follicular dendritic cell sarcoma.
DESIGN.—: Sixty-one UPS cases were screened by tissue microarray and an immunostain panel with subsequent analysis on whole block sections for suspicious cases.
RESULTS.—: Five of 61 tumors (8%) were suggestive of HS based on the screening panel and were further evaluated with additional immunostains (PU.1, CD45, CD163) using whole sections. The 5 candidate HS cases were only focally positive for at most one stain with most staining in smaller, less-pleomorphic cells. Ultimately, no UPS met criteria for anaplastic large cell lymphoma, diffuse large B-cell lymphoma, myeloid sarcoma, follicular dendritic cell sarcoma, or HS.
CONCLUSIONS.—: Our results suggest that a UPS of somatic soft tissue is unlikely to represent a misclassified hematopoietic malignancy. Exclusion of HS is most challenging, but immunostaining for PU.1, a nuclear transcription factor, may be easier to interpret in this context.
软组织未分化多形性肉瘤（UPS）被定义为一种无法识别分化谱系的肉瘤。在过去几十年中，辅助研究的进展以及对既往UPS诊断的回顾通过排除更具特异性的恶性肿瘤，缩小了UPS的范畴。然而，这些研究中很少有专门针对多形性血液淋巴系统肿瘤的。
确定UPS病例中有多少比例被错误分类为多形性血液淋巴系统肿瘤，如间变性大细胞淋巴瘤、弥漫性大B细胞淋巴瘤、组织细胞肉瘤（HS）、髓系肉瘤和滤泡树突状细胞肉瘤。
通过组织微阵列和免疫染色 panel 对61例UPS病例进行筛查，随后对可疑病例的整个切片进行分析。
61个肿瘤中有5个（8%）根据筛查 panel 提示为HS，并使用整个切片通过额外的免疫染色（PU.1、CD45、CD163）进行进一步评估。这5例候选HS病例最多仅在一种染色上呈局灶性阳性，且大多数染色见于较小、多形性较低的细胞。最终，没有UPS符合间变性大细胞淋巴瘤、弥漫性大B细胞淋巴瘤、髓系肉瘤、滤泡树突状细胞肉瘤或HS的标准。
我们的结果表明，躯体软组织的UPS不太可能代表错误分类的造血系统恶性肿瘤。排除HS最具挑战性，但在这种情况下，核转录因子PU.1的免疫染色可能更容易解释。
