Pathological Case of the Month FREE

Figure 1. Discrete intracortical densely enhancing lesion with sharp borders on T2-weighted image at the level of corpus striatum.

Figure 2. Spindle-shaped cells form whorls and ill-defined fascicles resembling a meningioma, mixed with a diffuse mononuclear infiltrate containing histiocytes (hematoxylin-eosin, original magnification ×40).

Figure 3. Most of the inflammatory cells express HLA-DR (A), CD20 (B), and CD68 (C) (avidin-biotin immunoperoxidase method, original magnification ×100).

Plasma cell granuloma is a rare pulmonary lesion of children and young adults, often discovered as an incidental mass on routine examination. A minority of cases catch clinical attention because of an associated syndrome of fever, anemia, and leukocytosis. Extrapulmonary plasma cell granuloma occurs in various locations. Other names given to this condition include inflammatory pseudotumor, xanthomatous pseudotumor, low-grade inflammatory fibrosarcoma, plasma cell pseudotumor, inflammatory meningeal mass of unexplained origin, meningioma with conspicuous plasma cell lymphocytic components, hyalinizing plasmacytic granulomatosis, inflammatory myofibrohistiocytic proliferation,¹ and inflammatory myofibroblastic tumor.²

In the intracranial location, plasma cell granuloma often presents with headache, seizure, paresis, vision disturbance, ataxia or vertigo, gait disturbance, and decreased consciousness. The intracranial localization varies; in a recent series of 29 cases, 8 were found to be intraparenchymal (6 of these were in the right frontal lobe), 19 were meningeal based, 1 had meningeal and parenchymal components, and 1 was unknown. In some cases, hematological abnormalities were commonly observed, including leukocytosis (5/8), hypochromic anemia (3/8), thrombocytosis (3/8), low ferritin levels (2/8), elevated erythrocyte sedimentation rate in most patients, and hypergammaglobulinemia (8/15).³ Histologically, the lesion is invariably composed of myofibroblasts, polyclonal plasma cells with Russell bodies, lymphocytes with or without germinal centers, and eosinophils. In neural tissue, one also frequently finds activated microglia and hypertrophic astrocytes.^3- 5 The presence of necrosis, calcification, and hemorrhage often imparts a more ominous appearance.¹ Immunophenotyping studies have revealed the presence of vimentin in almost all the lesions, particularly among the spindle-cell components (99%). Many of these also react with smooth muscle actin (92%) and desmin (69%). CD68 has been expressed in about 24% of cases.²

Other extrapulmonary sites reported have included the mesentery and/or omentum, the gastrointestinal tract, the genitourinary tract, the upper respiratory tract, the pelvis, the retroperitoneum, soft tissue, trunk (including heart, mediastinum, breast, inguinal area), extremities, and head and neck.² The cause is unknown. While various bacterial infections have been implicated, most cases have had negative culture findings.⁴ Findings for Epstein-Barr virus by in situ hybridization for a portion of the EBER-1 gene was positive in 7 (41.2%) of 18 patients in a recent study.⁶ The search for an origin is ongoing.

Accepted for publication June 4, 1999.

Reprints: Atilano Lacson, MD, Department of Pathology, All Children's Hospital, 801 Sixth St S, St Petersburg, FL 33701-8920.