BACKGROUND: Metastatic breast carcinoma (mBC) is frequently encountered and may be challenging to diagnose as the tumor cells can morphologically resemble carcinomas of other primary origins. An additional challenge is that direct smears are often the only sample type available for immunostaining studies in cytology. Trichorhinophalangeal syndrome GATAbinding type 1 1 (TRPS1) is a highly sensitive marker for BC compared to the commonly used marker GATA3, especially in triple-negative BC (TNBC), in histologic samples. However, its sensitivity and specificity in mBC and other GATA3-positive tumors have not been studied. METHODS: The authors identified the following cytology cases: 37 GATA3-positive mBC cases and 19 available cases that were deemed mBC but were GATA3-negative during the original case workup and five cases of each of eight epithelioid entities known to have high rates of GATA3 positivity and commonly seen in cytology practice. Immunostainings of TRPS1 and GATA3 were performed on the chosen smears following standard protocols. RESULTS: TRPS1 was positive in all 37 GATA3-positive mBC cases and in 18 of the 19 GATA3-negative mBC cases. TRPS1 was negative in all five of the seven frequently GATA3-positive epithelioid entities, with the exception of salivary duct carcinomas where GATA3 was positive in a rate ranging 60%-100% among them. CONCLUSIONS: TRPS1 is as sensitive as GATA3 in GATA3positive mBC and is more sensitive than GATA3 in TNBC. TRPS1 is negative in most GATA3-positive nonbreast tumors. Thus, the combination of TRPS1 and GATA3 could be used to differentiate breast primary from others in most situations.

Objectives Primary pancreatic lymphoma (PPL) is rare, mimicking pancreatic ductal adenocarcinoma (PDAC) clinically and radiologically. The aim of this study is to evaluate the clinical, radiologic, and pathological characteristics of PPL diagnosed by fine-needle aspiration (FNA) in our institution. Methods Patient clinical, radiologic, and pathological information was collected from the electronic health record system. Results In total, 11 of 4,353 pancreatic FNAs met the criteria. The most common clinical symptom was jaundice, followed by abdominal pain, weight loss, and diarrhea. Abnormal laboratory findings included elevated alkaline phosphatase, total bilirubin, lactate dehydrogenase, and cancer antigen 19-9. Abnormal radiologic findings included pancreatic mass, biliary dilatation, vessel encasement, and common bile duct encasement and thickening. Five patients underwent more than 1 tissue sampling procedure before the final diagnosis of lymphoma. Final pathologic diagnosis included 7 large B-cell lymphomas and 4 follicular lymphomas. Flow cytometric analysis was performed on 9 specimens, and all demonstrated an aberrant monoclonal B-cell population. Conclusions PPL mimics PDAC clinically and radiologically and could be a challenge for pathologic diagnosis if lymphoma is not included in the differential diagnosis during immediate evaluation. If lymphoma is suspected during immediate evaluation, PPL could be reliably diagnosed by FNA with the aid of ancillary studies.