Factor XIII Subunit A Immunohistochemical Expression is Associated With Inferior Outcomes in Acute Promyelocytic Leukemia.

Coagulation factor XIII subunit A (FXIIIa) intracellular expression has been described in platelets, megakaryocytes, monocytic cells, and leukemic blasts. Flow cytometric-based studies have suggested prognostic implications of FXIIIa expression, especially within the acute promyelocytic leukemia (APL) subgroup of acute myeloid leukemia (AML); however, its prognostic correlate by immunohistochemistry (IHC) is unknown. The aims of this study were to (1) define the clinicopathologic features of FXIIIa IHC-positive AML and (2) compare APL with other AML subtypes. Eighty-seven bone marrow biopsies or clot/particle preparations from our institution were evaluated with FXIIIa IHC. The study cohort consisted of bone marrow evaluations of 36 consecutive pretherapy APL, 42 selected pretherapy non-APL AML, and 9 negative staging cases. FXIIIa IHC expression was correlated with clinical and pathologic features and overall survival (OS). Leukemic blast FXIIIa cytoplasmic positivity was noted in 56% (20/36) APL and 74% (31/42) non-APL AML (P=0.10). FXIIIa IHC expression was associated with inferior OS within the APL cohort (P=0.04). No OS differences were noted in comparing FXIIIa IHC expression in all AML (P=0.17), or FXIIIa IHC expression within favorable, intermediate or adverse cytogenetic groups (P=0.14, 0.22 and 0.87, respectively). FXIIIa IHC expression is observed among a broad spectrum of AML subtypes and is not characterized by specific pathologic features. However, within the APL subgroup, FXIIIa IHC expression is associated with an inferior outcome and may be useful for additional prognostic risk stratification.

The influence of the noninvasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP) resection diagnosis on the false-positive thyroid cytology rate relates to quality assurance thresholds and the application of NIFTP criteria.

BACKGROUND: Noninvasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP) is a newly defined entity and recent studies have suggested a decrease of a few percentage points in the rate of malignancy (ROM) for the positive-for-malignancy (PFM) cytology category as a result of NIFTP implementation. However, the distinction between a diagnosis of PFM and one of suspicious for malignancy (SFM) may depend on a variety of factors. In the current study, the authors investigated the ROM for the PFM and SFM diagnoses before and after histologic NIFTP reclassification. METHODS: Cytology cases with PFM and SFM diagnoses and subsequent surgical resection specimens were searched in the files of the study institution from September 2008 to September 2016. The surgical pathology cases of noninvasive encapsulated follicular variant of papillary thyroid carcinoma were reexamined to determine whether they qualified for NIFTP. The distinct ROMs for the PFM and SFM cases were calculated accordingly. RESULTS: The authors' search identified 338 cases of PFM and 139 cases of SFM with a resection outcome. Before NIFTP reclassification, the PFM cases had a ROM of 99.4%; after NIFTP reclassification, the ROM was 99.1% (P = .6861). The ROM of the SFM cases decreased from 75.5% to 66.9% with NIFTP reclassification (P = .1402). One case in the PFM group and 6 cases in the SFM group could not be verified due to insufficient sampling. CONCLUSIONS: In the current large series, NIFTP reclassification did not appear to significantly alter the high ROM for the PFM diagnosis. The authors attribute this finding to a strict quality assurance policy, an emphasis on key cytologic criteria, and systematic application of the NIFTP criteria to follicular-patterned lesions. Cancer Cytopathol 2017;125:692-700. © 2017 American Cancer Society.

Evaluating breast lymphoplasmacytic infiltrates: a multiparameter immunohistochemical study, including assessment of IgG4.

Lymphoplasmacytic infiltrates in the breast, a modified skin appendage, include lymphocytic lobulitis, other nonspecific benign proliferations, and mucosa-associated lymphoid tissue (MALT)-type lymphoma. Distinguishing these entities, all of which may be B-cell rich and may have associated sclerosis, can be difficult. In addition, the proportion that represents IgG4-related disease is unknown, and the similarity of MALT lymphomas to primary cutaneous marginal zone lymphoma is uncertain. To address these questions, the clinical, histologic, and immunohistochemical features of 50 benign and malignant breast lymphoplasmacytic infiltrates (10 lymphocytic lobulitis, 1 granulomatous, 19 not otherwise specified, 20 MALT lymphomas) were evaluated. Compared with the MALT lymphomas, benign cases had a less dense infiltrate (P < .001), fewer but more histologically apparent germinal centers (P < .001), and more marked fibrosis (P < .0001). Greater than 60% B cells were present in 23% (7/30) benign cases versus 75% (15/20) MALT lymphomas (P = .0003). Plasma cells were predominantly IgG+ in 83% (24/29) benign cases and predominantly IgM+ in 73% (14/19) MALT lymphomas (P < .0001). None of the benign cases had greater than 50 IgG4+ plasma cells/high-power field, and only 1 lymphocytic lobulitis case had an IgG4/IgG ratio exceeding 40% and no clinical evidence for extramammary IgG4-related disease. Although there may be some overlapping features, routine histopathology together with limited immunohistochemical stains can distinguish benign from neoplastic lymphoplasmacytic infiltrates in the breast. Despite frequent sclerosis, the breast is not a common site of unrecognized IgG4-related sclerosing disease. Although there are similarities, breast MALT lymphomas can be separated from cutaneous marginal zone lymphoma.