Mycobacterial spindle-cell pseudotumor of the spleen
Arkadi M. Rywlin Department of Pathology and Laboratory Medicine, Mount Sinai Medical Center, Miami Beach, FL 33140.American Journal of Clinical Pathology (Impact Factor: 2.51). 05/1994; 101(4):539-42.
A case of spindle-cell pseudotumor of the spleen due to nontuberculous mycobacteria in a patient with acquired immunodeficiency syndrome (AIDS) is described. The patient was a 55-year-old, human immunodeficiency virus-positive Haitian man who died of acute neurologic complications while on treatment for central nervous system toxoplasmosis. At autopsy, an enlarged multinodular spleen was noted. Histologic examination revealed coarse nodules of splenic parenchyma replaced by a dense spindle cell proliferation, admixed with scattered inflammatory cells. Immunostains showed strong cytoplasmic positivity of the spindle cells with MAC 387, HAM 56, and alpha-1-antichymotrypsin antibodies and negative staining for actin, vimentin, and S-100 protein antibodies. Ziehl-Neelsen stains revealed numerous elongated acid-fast bacilli within the cytoplasm of the cells that were occasionally lying free within the interstitium. The organisms also had a strongly positive reaction with antibodies to desmin intermediate filaments. Mycobacterial spindle-cell pseudotumor should be included in the differential diagnosis of conditions affecting the spleen in patients with AIDS.
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ABSTRACT: Inflammatory pseudotumor is a presumably nonneoplastic, hematopoietic, and spindled fibrous proliferation that may occur at a variety of anatomic sites. The origin of these proliferations is generally unknown. To evaluate the role of the Epstein-Barr virus (EBV) in inflammatory pseudotumor, 18 specimens from 17 patients were studied by in situ hybridization for EBV ribonucleic acid (RNA), and the morphological and immunologic characteristics of the infected cells were evaluated. These specimens included 10 lymph nodes, six splenic masses, and two hepatic masses. Overall, EBV RNA was detected in 41.2% (seven of 18) of the cases. These included two of 10 (20%) lymph nodes, four of six (66.7%) splenic pseudotumors, and one of two (50%) hepatic lesions. The degree of EBV infection was significantly greater within the tumors in comparison with the surrounding, uninvolved tissue. Two morphologically different EBV-positive cell types, spindled and round cells, were evident, and the infected cell type differed significantly when the nodal and extranodal cases were compared. All of the positive extranodal cases shown, numerous EBV-positive spindled cells, whereas no positive spindle cells (only positive round cells, morphologically consistent with lymphocytes) were noted in the two EBV-positive lymph node pseudotumors. Double-labeling immunohistochemical and in situ hybridization studies in some cases identified rare EBV-positive B cells and rare EBV positive T cells in four and three cases, respectively. Most EBV-positive cells in all cases failed to immunoreact with any B- or T-cell markers. Three of five cases studied, however, did show a subpopulation of smooth muscle actin/EBV-positive spindled cells, five of seven cases showed vimentin/EBV-positive spindled cells, and one of four cases had EBV-positive spindled cells that immunoreacted as follicular dendritic cells. These results suggest that EBV plays a role in a significant number of cases of inflammatory pseudotumor with differences in the incidence of EBV infection and the cell type (spindled vs round cell) infected when extranodal and nodal cases are compared, suggesting a difference in pathogenesis. The cell type infected in extranodal cases seemed to be of mesenchymal origin but could not be clearly defined.Human Pathlogy 11/1995; 26(10):1093-8. DOI:10.1016/0046-8177(95)90271-6 · 2.77 Impact Factor
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ABSTRACT: Inflammatory pseudotumor (IPS) of the urinary bladder was first described in 1980. We report four cases of IPS which occurred during the last four years. One tumor occurred in the bladder of a 49-year-old woman five months after abdominal hysterectomy of uterine leiomyomas, two tumors in a 35- and 39-year-old woman, respectively, without antecedental surgical intervention (though one with recidive after six months). The fourth occurred in a 64-year-old male in the proximal ureter by pyelonephritis. Two cases were initially diagnosed at frozen section during operative treatment, the others on paraffine section after immunohistochemical examination. Two cases showed an aberrant expression of cytokeratines. There is no evidence of recidive tumor within a mean follow up of 25 months (12-49 months). Features to differentiate benign from malignant spindle cell lesions of the lower urinary tract are the absence of atypical mitoses, significant cytologic atypia, absence of necroses within the tumor (rather on its surface), no destructive growth at the tumor margins and low cellularity. Usually, IPS show a submucosal edematous area with a deeper, highly cellular component. The clinical history of a recent bladder operation or gynecologic surgery is of upmost importance in making the diagnosis of IPS. Complete surgical excision, either by transurethral resection or partial cystectomy appears to be curative for IPS.Pathology - Research and Practice 01/1997; 193(9):607-12. DOI:10.1016/S0344-0338(97)80037-4 · 1.40 Impact Factor
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ABSTRACT: The inflammatory pseudotumour is a bona fide tumour in the sense of a mass lesion, which is known to present in virtually every anatomic region and organ from the central nervous system to the gastrointestinal tract. A fundamental question about pathogenesis is whether the inflammatory pseudotumour is a pseudo-or true neoplasm. There is evidence to support the argument that some of these fibroinflammatory masses are infection-associated and are often characterized by a proliferation of spindled histiocytes and/or dendritic cells, in contrast to a myofibroblastic proliferation in the other inflammatory pseudotumour, also known as the inflammatory myofibroblastic tumour.The Journal of Pathology 11/2000; 192(3):277-9. DOI:10.1002/1096-9896(200011)192:3<277::AID-PATH749>3.0.CO;2-E · 7.43 Impact Factor
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