LAUSR

A 47-year-old woman presented with left axillary lymphadenopathy for 2 years. Computed tomography demonstrated multiple enlarged axillary lymph nodes up to 4 cm in size. Excisional biopsy of an axillary lymph node showed reactive follicular hyperplasia. In addition, there were few crescent-like perifollicular granulomas encircling lymphoid follicles (Figure 1A). The granulomas were composed of epithelioid histiocytes and occasional multinucleate giant cells (Figure 1B). Immunohistochemical studies revealed numerous IgG4-positive plasma cells (>100 per high-power field) within germinal centers (Figure 1C). The ratio of IgG4-positive plasma cell to IgGpositive plasma cell was close to 100%. The serum IgG4 level was 552 mg/dL (reference range = 3-201 mg/dL), while the serum IgG, IgM, and IgA levels were within normal limit. No pancreatic, orbital, or salivary involvement was noted, but the increased IgG4-positive plasma cells and elevated serum IgG4 were consistent with IgG4related lymphadenopathy. There are 5 major histological patterns of IgG4-related lymphadenopathy: multicentric Castleman disease-like, follicular hyperplasia, interfollicular expansion, progressive transformed germinal center-like, and nodal inflammatory pseudotumor-like. Besides these major patterns, epithelioid granulomas have been reported in IgG4-related lymphadenopathy. The extent of granulomatous reaction varies. In particular, a distinct granulomatous reaction called perifollicular granuloma has been described. The epithelioid granulomas are arranged in a concentric or crescent-like fashion encircling lymphoid follicles. Siddiqi et al suggested perifollicular granuloma is specific to increased IgG4-positive plasma cells in germinal centers. Lack of complete clinical information and serum IgG4 level, the association of perifollicular granuloma and IgG4-related disease remains unclear. Reactive follicular hyperplasia is an extremely common finding in lymph node biopsy, and the great majority of cases are unrelated to IgG4. Without clinical history of IgG4-related disease, it is difficult to recognize IgG4-related reactive follicular hyperplasia. Although the clinical significance and specificity have not been well investigated, we believe perifollicular 708609 IJSXXX10.1177/1066896917708609International Journal of Surgical Pathology research-article2017