Plexiform Fibrohistiocytic Tumor
Definition
- Biphasic neoplasm centered in the high subcutaneous tissue with plexiform ray-like extensions of fibrous tissue into the surrounding fat usually with nodules of histiocyte-like cells
Alternate / Historical Names
-
Plexiform fibrous histiocytoma
Diagnostic Criteria
- Poorly circumscribed mass centered in the high subcutis
- Plexiform rays of fibrous tissue extend into the surrounding fat
- Occasionally extends into high dermis or underlying muscle
- Biphasic process
- Nodules of histiocyte-like cells and multinucleated giant cells
- Rare mitotic figures and no pleomorphism
- Pale granular cytoplasm
- May have intranodular hemorrhage and hemosiderin
- May have surrounding lympho-plasmacellular infiltrate
- Bland spindled fibroblasts with associated collagen
- Rare mitotic figures and no pleomorphism
- Surround the nodules of histiocyte-like cells
- Form the plexiform rays
- Resembles fibromatosis
- May hyalinize or rarely ossify
- Proportion of the two components is variable
- Nodules of histiocyte-like cells are absent in some cases
- Nodules of histiocyte-like cells and multinucleated giant cells
- Intravascular and perineural involvement have been reported
- Uncertain significance
- A similarity and possible relationship to cellular neurothekeoma has been proposed (Jaffer)
Richard L Kempson MD
Robert V Rouse MD
Department of Pathology
Stanford University School of Medicine
Stanford CA 94305-5342
Original posting/updates: 8/10/08, 1/6/10
