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Soft Tissue Tumors
Malignant fibrous histiocytoma of soft tissue - inflammatory
Author: Nat Pernick, M.D., PathologyOutlines.com, Inc.
Reviewer: David Lucas, M.D., University of Michigan Health Systems (January 2009)
Revised: 5 October 2009, last major update June 2009
Definition
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● Neoplastic histiocyte-like cells mixed with, and often obscured by neutrophils and other inflammatory cells
Terminology
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● Most of these tumors are probably dedifferentiated liposarcoma (J Pathol 2004;203:822, see also Pathol Int 1997;47:642) or leiomyosarcoma
● Diagnosis of exclusion; recommended to take many sections and use immunohistochemistry to rule out mimics
Clinical
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● Very rare, usually age 40+ years, often retroperitoneal
● May be associated with fever, leukocytosis (leukemoid reaction) and eosinophilia
● May occur in skin with predominance of lymphocytes (Am J Dermatopathol 2002;24:251)
● Very aggressive with poorest prognosis of all MFH types (2/3 die of disease, 1/4 have distant metastases) although these studies probably included other morphologically similar disorders
Case reports
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● 4 year old boy with chest wall swelling (Fetal Pediatr Pathol 2004;23:319)
● 63 year old man with abdominal tumor (Case of Week #144)
Gross description
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● 8-10 cm, yellow due to xanthoma cells; firm, lobulated
Micro description
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● Commonly has storiform pattern, background of inflammatory cells (histiocyte-like, xanthoma, neutrophils, lymphocytes, eosinophils, plasma cells) which may obscure tumor cells
● Tumor cytoplasm may contain phagocytized neutrophils; nuclei are large and vesicular with prominent nucleoli
● May have bizarre giant cells or atypical mitotic figures but no necrosis
Micro images
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Acute inflammatory cells and Large histiocyte-like cells with prominent
large histiocyte-like cells nucleoli resembling lymphoma or carcinoma,
with variable fibroblasts
Numerous histiocyte-like cells Associated with orthopedic implant
resembling lymphoma
Abdominal tumor:
HMB-45 Melan-A
Cytology description
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● Neutrophilic infiltrate in and around tumor cells, which show prominent neutrophilic phagocytosis (Fetal Pediatr Pathol 2004;23:319)
Positive stains
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● MDM2, CDK4 (these cases may actually be dedifferentiated liposarcoma)
Molecular / cytogenetics
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● 12q13-15 amplification or gain (these cases may actually be dedifferentiated liposarcoma)
Differential Diagnoses
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● Myxoid or dedifferentiated liposarcoma (may need to submit additional sections of normal appearing fat to identify, perform MDM2 or CDK4 or obtain cytogenetics)
● Irradiated osteosarcoma
● Metastatic renal or adrenal carcinoma
● Reactive abscess-like lesion
● Xanthogranulomatous pyelonephritis (Int J Urol 2006;13:1000)
● Inflammatory myofibroblastic tumor
● Hodgkin’s or anaplastic lymphoma (Mod Pathol 1997;10:438)
● Melanoma
End of Malignant fibrous histiocytoma of soft tissue > inflammatory
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