External Quality Assurance of Platelet Function Assays: Results of the College of American Pathologists Proficiency Testing Program.

CONTEXT.­: The College of American Pathologists (CAP) developed proficiency testing for platelet function assays by using blood collected by the participant added to challenge tubes containing either saline (normal) or tirofiban (abnormal). OBJECTIVE.­: To analyze platelet function proficiency testing for Platelet Function Analyzer PFA-100, platelet aggregation, PlateletWorks, and PlateletMapping. DESIGN.­: Proficiency testing data from 2012-2016 were analyzed. RESULTS.­: For PFA-100, a total of 1200 laboratories participated; the coefficient variation (CV) of cartridge closure times was 22% (saline); 44,952 of 45,616 survey responses (99%) provided an interpretation, and 42,934 of 44,952 (96%) were correct. For optical platelet aggregation, 190 laboratories participated; the CV was 17% (saline), 7444 of 7813 survey responses (95%) provided an interpretation, and 7015 of 7444 (94%) were correct. For PlateletWorks, 60 laboratories participated; the CV was 3% to 11% (saline); 2412 of 2454 survey responses (98%) provided an interpretation, and 1207 of 1276 (95%) were correct for adenosine diphosphate (ADP) and 936 of 1136 (82%) for collagen. For PlateletMapping, 200 laboratories participated. For ADP, 1128 of 2697 survey responses (42%) provided an interpretation, but only 927 of 1128 (82%) were correct. For arachidonic acid, 1139 of 2604 survey responses (44%) provided an interpretation and 964 of 1139 (85%) were correct. CONCLUSIONS.­: CAP is the first to provide proficiency testing for platelet aggregation, PlateletWorks, and PlateletMapping. Platelet aggregation, PFA-100, and PlateletWorks using ADP as an agonist performed well with more than 90% of laboratories providing an interpretation and a similar number providing correct results. PlateletWorks using collagen and PlateletMapping showed worse interpretive accuracy than the other methods.

Primary Central Nervous System Histiocytic Sarcoma Arising After Precursor B-Cell Acute Lymphoblastic Leukemia.

Histiocytic sarcomas (HSs) are rare malignant neoplasms derived from histiocytes that may be associated with other hematolymphoid neoplasms. Histiocytic sarcomas rarely occur in the CNS and have not previously been reported in conjunction with prior B-cell lymphoblastic leukemia. We report the case of a 23-year-old man who presented with primary CNS HS 7 years after achieving remission for precursor B-cell acute lymphoblastic leukemia (B-ALL). Molecular studies revealed clonal immunoglobulin heavy-chain (IGH) gene rearrangement within the HS, suggesting linkage to his previous B-ALL. Previously reported post-ALL HSs show a strong predilection for young males (male-to-female ratio, 20:1), whereas cases of primary CNS HS without previous ALL affected older adults with balanced sex predilection. The patient's survival at 60 months exceeds expectations when compared with that of other reported cases of de novo primary CNS HS (n = 18) and post-ALL HS at all sites (n = 19). In addition, we discuss the potential relationship between B-ALL and HS posed by other authors.

Tissue-preserving antibody cocktails to differentiate primary squamous cell carcinoma, adenocarcinoma, and small cell carcinoma of lung.

CONTEXT: With the availability of cell type-specific therapies, differentiating primary lung squamous cell carcinomas (SCCs) and adenocarcinomas (ACAs) has become important. The limitations of small sample size and the need to conserve tissue for additional molecular studies necessitate the use of sensitive and specific marker panels on a single slide. OBJECTIVE: To distinguish SCC from ACA and small cell carcinoma (SmCC) of lung using 2 novel tissue-conserving cocktails. DESIGN: We compared two antibody cocktails, desmoglein 3 + cytokeratin 5/napsin A and p40/thyroid transcription factor 1 (Biocare Medical, Concord, California) in diagnosing SCC and ACA of the lung on tissue microarray, cytology, and surgical specimens. Both lung and nonlung tissue were evaluated on an 1150-core tissue microarray that contained 200 lung cancers. A microarray of 35 SmCCs and 5 small cell SCCs was also evaluated. RESULTS: A cocktail of desmoglein 3 + cytokeratin 5/napsin A provided diagnostic accuracy in lung cancers with a sensitivity and specificity of 100% in SCCs and a sensitivity of 86% and a specificity of 100% in ACAs. A p40/thyroid transcription factor 1 cocktail showed p40 to have a specificity of 92% and a sensitivity of 93% in SCCs, whereas thyroid transcription factor 1 had a specificity of 100% and a sensitivity of 77% in ACAs. Cell blocks of fine-needle aspiration cytology compared with corresponding surgical (n = 20) specimens displayed similar findings. The p40 was useful in differentiating bladder from prostate carcinoma with 88% sensitivity. Isolated carcinomas from nonlung tissues were desmoglein 3 + cytokeratin 5 positive. Napsin A was positive in 22% of renal tumors as previously observed. Both cocktails were excellent in differentiating SmCCs and small cell SCCs because none of the SmCCs stained with p40. CONCLUSIONS: Both antibody cocktails are excellent in differentiating primary lung ACA from SCC, as well as excluding SmCC and ACAs from all other sites on small specimens. A cocktail of desmoglein 3 + cytokeratin 5/napsin A is slightly superior compared with p40/thyroid transcription factor 1 cocktail.