Background. Pulmonary inflammatory pseudotumor, also known as plasma cell granuloma among many other names, is widely believed to be an inflammatory or reactive lesion rather than a neoplasm, although its pathogenesis is still controversial. Methods. Cytogenetic analysis was performed on a lung mass that showed typical clinical and pathologic features of inflammatory pseudotumor. Ultrastructural and immunohistochemical studies were performed in addition to routine histologic examination. Results. Cytogenetic study of the lesion revealed clonal anomalies of t(1;2)(q21;p23) and del(4)(q27). The patient, a 30‐year‐old woman, presented with an asymptomatic but enlarging right lower lobe mass for which partial right lower lobectomy was performed. The lung mass was well circumscribed radiographically and grossly. Microscopically, it was characterized by a loosely arranged spindle cell proliferation with prominent plasma cell infiltration. Fibroblastic and myofibroblastic differentiation of the spindle cells was demonstrated by ultrastructural and immunohistochemical studies. Conclusion. To the authors' knowledge, this is the first report of clonal cytogenetic changes in a clinically and pathologically typical case of inflammatory pseudotumor in the lung. This finding suggests that pulmonary inflammatory pseudotumor might be a true neoplasm rather than a purely inflammatory or reactive lesion. Cancer 1995; 76:1545‐9.

GS especially can be confused with non-Hodgkin lymphoma because of morphologic similarities of the blasts to large cell lymphoma, the presence of lymphoglandular bodies, and the rarity of Auer rods and eosinophilic myelocytes. In conjunction with careful cytomorphologic evaluation, knowledge of the patient's clinical history and use of appropriate immunophenotypic studies should lead to a correct diagnosis.

BACKGROUND Because of morphologic similarities, the differential diagnosis of granulocytic sarcoma (GS) in fine‐needle aspiration (FNA) specimens includes non‐Hodgkin or Hodgkin lymphoma, extramedullary hematopoiesis, poorly differentiated carcinoma, and infection. METHODS Twenty‐six FNAs and 1 pleural effusion fluid specimen of GS obtained from 23 patients were reviewed for cytomorphologic features and clinical characteristics. The cases were categorized as blastic, immature, or mature GS based on the population of the cells present on the smears. RESULTS The patients included 18 men and 5 women (mean age, 54 years). Aspiration sites included subcutaneous or soft tissue (15 cases), lymph nodes (5 cases), bones (3 cases), testis (1 case), ileum (1 case), and liver (1 case). One sample of pleural effusion fluid also was included. Review of the patients' clinical history revealed that GS was secondary to chronic myelogenous leukemia (CML) in 17 patients, was secondary to chronic myelomonocytic leukemia (CMML) in 2 patients, and was secondary to acute myelogenous leukemia in 2 patients. GS preceded the manifestation of CML in one patient and of CMML in another patient. Based on the proportions of cells, morphologic classification was attempted and revealed blastic GS in 8 aspirates and 1 pleural effusion fluid specimen, immature GS in 13 aspirates, and mature GS in 5 aspirates. Twelve of 22 specimens from extranodal sites (55%) demonstrated lymphoglandular bodies in the background. Five aspirates showed rare eosinophilic myelocytes. Auer rods were not identified in any of the aspirates. Immunophenotypic and histochemical studies confirmed myeloid and/or myelomonocytic differentiation. CONCLUSIONS GS especially can be confused with non‐Hodgkin lymphoma because of morphologic similarities of the blasts to large cell lymphoma, the presence of lymphoglandular bodies, and the rarity of Auer rods and eosinophilic myelocytes. In conjunction with careful cytomorphologic evaluation, knowledge of the patient's clinical history and use of appropriate immunophenotypic studies should lead to a correct diagnosis. Cancer (Cancer Cytopathol) 2000;90:364–372. © 2000 American Cancer Society.

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Among the various types of lymphoma, follicular lymphoma (FL) is known to have significant limitations in cytologic diagnosis by the fine‐needle aspiration (FNA) method. The diagnostic accuracy (DA) for non‐Hodgkin's lymphoma (NHL) by FNA was evaluated by review of 82 cases of histologically proved NHL after prior FNA. The DA for all NHLs was 66% (54/82), and that for low‐grade lymphomas, including small lymphocytic lymphoma, follicular small‐cleaved cell lymphoma, and follicular mixed cell lymphoma, was 71% (12/17). The DA for FL was 69% (11/16). Review of individual surgical and cytologic materials from FLs revealed a tendency to show fibrosis in the cytologically false‐negative group and diffuse areas of lymphoma in the true‐positive group. The presence of “aggregation” of uniform lymphoid cells, probably due to cell adhesions with the support of dendritic reticulum cells, was seen in 55% of true‐positive FL (6/11). In contrast, only 28% of true‐positive diffuse large cell lymphomas (5/18) showed a mild degree of aggregation, and none of 7 cases of true‐positive diffuse small‐cleaved cell lymphoma showed this feature. The aggregation of cells was not pathognomonic of FL, but its presence with a homogeneous cellular constituent and the paucity of tingible‐body macrophages helped us to predict FL. Also, it was a feature distinguishing FL from diffuse small‐cleaved cell lymphoma (P = 0.025). Diagn. Cytopathol. 1997;17:467–471. © 1997 Wiley‐Liss, Inc.