Policarpio-Nicolas, Maria Luisa C

AbstractBackgroundAutoimmune pancreatitis (AIP) is a known mimicker of pancreatic ductal adenocarcinoma both clinically and radiologically. In this study, the authors present their institutional experience in diagnosing AIP on cytology and correlate results with the histologic findings.MethodsA 14‐year computerized search for patients who had histologically confirmed AIP with concurrent or prior cytology was performed. Clinical data, cytology findings, and surgical pathology results were reviewed for analysis.ResultsEighteen patients were identified. The patients showed a male predominance, with a mean age of 59 years. Jaundice, weight loss, and abdominal pain were the most common clinical presentation. Five of 12 patients who were tested for serum immunoglobulin G4 had elevated levels. Cytologic findings of 16 cases that were available for review showed markedly inflamed fibrous stroma (54%) and cytologic atypia (50%). The final cytologic diagnoses were suspicious for adenocarcinoma (n = 1), atypical (n = 8), and benign/negative (n = 9). The corresponding surgical pathology diagnoses were classified as type 1 (n = 10), type 2 (n = 6), and AIP, not otherwise specified (n = 2). All type 2 AIP cases had at least atypical cytologic diagnoses, with one called suspicious for adenocarcinoma and another called adenocarcinoma at the time of rapid on‐site evaluation. In contrast, eight of 10 type 1 AIP cases were negative/benign, and two of 10 were atypical. In these two atypical cases, the possibility of AIP was raised because of the presence of inflamed stroma.ConclusionAIP is a pitfall in cytology because moderate‐to‐marked atypia can be present, especially in type 2 AIP. Because atypia can be severe, the presence of cellular fibrous stroma with lymphocytic stromal infiltrates and the integration of serum immunoglobulin G4 levels could be helpful in avoiding diagnostic overcall in AIP.

BackgroundThe literature on bone and soft tissue sarcomas (BSTSs) involving effusions and cerebrospinal fluid (CSF) is very limited.MethodsA computerized search for fluid cytology with a sarcoma diagnosis from 2000 to 2020 was performed. All available cases, including the clinical follow‐up, were reviewed.ResultsA total of 57 fluids specimens from 36 BSTSs were identified (9 rhabdomyosarcomas, 6 angiosarcomas, 5 epithelioid hemangioendotheliomas, 3 dedifferentiated liposarcomas, 2 chondrosarcomas, 1 extraskeletal myxoid chondrosarcoma, 3 Ewing sarcomas, 2 undifferentiated sarcomas, 3 osteosarcomas, 1 synovial sarcoma, and 1 hybrid low‐grade fibromyxoid sarcoma/sclerosing epithelioid fibrosarcoma). There were 22 males and 14 females. The age range was 4 to 82 years (median, 45 years). Sites of involvement included pleural fluid (n = 38), peritoneal fluid (n = 14), and CSF (n = 5). Twenty‐four cytology cases were available for review. The cytologic features were nonspecific and ranged from dyshesive to clusters of round, epithelioid, pleomorphic, and occasionally spindle‐shaped malignant cells that could easily mimic other non‐BSTS malignant tumors. The diagnosis of BSTS was made by comparison with a prior specimen and/or ancillary studies (molecular or immunohistochemical stains). The prognosis was poor because 95% of the patients died of their disease.ConclusionsThe incidence of BSTS in fluid cytology is extremely rare, and it can have cytologic features similar to those of non‐BSTS malignancies. Although, in most cases, a comparison with a prior known BSTS specimen may suffice, the use of ancillary studies is extremely helpful in arriving at the correct diagnosis. However, in cases with no known prior malignancy, including BSTS in the differential diagnosis is prudent for preventing misdiagnosis.