Follicular pancreatitis: a distinct form of chronic pancreatitis-an additional mimic of pancreatic neoplasms.

Follicular pancreatitis is a recently described variant of chronic pancreatitis characterized clinically by the formation of a discrete pancreatic mass and histologically by the presence of florid lymphoid aggregates with reactive germinal centers. Our aim was to study the clinical and histologic features of follicular pancreatitis, as well as to critically examine potential overlap with autoimmune pancreatitis. Immunohistochemistry for Bcl-2, CD21, κ and λ light chains as well as IgG4 and IgG were performed. We found a total of 6 patients (male-female ratio, 2:1; mean age, 57 years) who fulfilled the diagnosis of follicular pancreatitis in our institutions. Four had an incidental diagnosis, while two presented with abdominal pain, fatigue, and elevated liver enzymes. On imaging, 3 patients had a discrete solid mass, whereas 2 cases showed a dilated main pancreatic duct, mimicking an intraductal pancreatic mucinous neoplasm on imaging. One patient had a lesion in the intra-pancreatic portion of the common bile duct. On histopathology, all cases showed numerous lymphoid follicles with Bcl-2-negative germinal centers either in a periductal or in a more diffuse (periductal and intra-parenchymal) fashion, but without attendant storiform fibrosis, obliterative phlebitis, or granulocytic epithelial lesions. IgG4-to-IgG ratio was <40% in 5 cases. A comparison cohort revealed germinal centers in 25% of type 1 autoimmune pancreatitis and 2% of type 2 autoimmune pancreatitis cases, but none were periductal in location. In conclusion, follicular pancreatitis, an under-recognized mimic of pancreatic neoplasms is characterized by intrapancreatic lymphoid follicles with reactive germinal centers.

The value of fluorescence in situ hybridization and polymerase chain reaction in the diagnosis of B-cell non-Hodgkin lymphoma by fine-needle aspiration.

CONTEXT: Molecular genetic analyses have been predicted to improve the diagnostic accuracy of fine-needle aspiration of B-cell non-Hodgkin lymphoma. OBJECTIVE: To determine the value of routine molecular genetic assays, polymerase chain reaction (PCR) and fluorescence in situ hybridization (FISH), in the diagnosis of B-cell non-Hodgkin lymphoma by fine-needle aspiration (FNA). DESIGN: A multiparametric method, including cytology, flow cytometry, PCR, and FISH, was prospectively evaluated in the diagnosis of B-cell non-Hodgkin lymphoma by FNA. Aspirates from 30 consecutive patients with suspected hematolymphoid malignancies were collected. All aspirates were triaged through a uniform program including cell-size analysis, B- and T-cell clonality studies, flow cytometric immunophenotyping, and bcl-1 and bcl-2 gene rearrangements by PCR and FISH. After completion of FNA evaluations, FNA results were compared with diagnoses from prior or subsequent surgical biopsies. RESULTS: Monoclonal B-cell populations were detected in 18 of 20 B-cell non-Hodgkin lymphomas by flow cytometry and PCR. bcl-1 gene rearrangement was detected in 2 of 2 cases of mantle cell lymphoma. bcl-2 rearrangement was detected in 5 cases including 4 of 4 low-grade follicular lymphomas and 1 transformed follicular lymphoma. By incorporating the results of molecular genetic and ancillary diagnostics, a definitive classification was reached in 12 cases of B-cell non-Hodgkin lymphoma by FNA, including all cases of low-grade follicular lymphoma (4/4) and mantle cell lymphoma (2/2) and approximately 50% of small lymphocytic lymphoma (2/4) and large B-cell lymphoma (4/8). Ten of the 12 cases with a final classification reached by FNA had either prior or follow-up surgical biopsies, and all 10 cases showed agreement between the diagnoses rendered on FNA and surgical biopsies. CONCLUSIONS: With proper handling and management of specimens, FNA can routinely provide samples adequate for molecular genetic studies, in addition to cytomorphology and flow cytometry, making it possible to consistently render accurate and definitive diagnoses in a subset of B-cell non-Hodgkin lymphomas. By incorporating FISH and PCR methods, FNA may assume an expanded role for the primary diagnosis of B-cell non-Hodgkin lymphoma.