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
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
Ray-like extension of fibrous tissue into surrounding fat
Infiltrates between and around individual fat cells
Lacks pseudovascular spaces
Pseudovascular spaces present
Nodules of histiocytes and giant cells in most cases
Scattered individual giant cells
CD34 negative
CD34 stains lesional cells
Clinical
Mean age 15-20 years
May occur at any age
Most frequent in upper extremity
May involve wide variety of other sites
Approximately 1/3 recur
Not destructive or uncontrolled
Metastases rare
Regional lymph nodes
Lung
Bibliography
Kempson RL, Fletcher CDM, Evans HL, Henrickson MR, Sibley RS. Tumors of the Soft Tissues, Atlas of Tumor Pathology, AFIP Third Series, Fascicle 30, 2001
Fletcher CDM, Unni KK, Mertens F. Pathology and Genetics of Tumours of Soft Tissue and Bone, World Health Organization Classification of Tumours 2002
Weiss SW, Goldblum JR. Enzinger and Weiss's Soft Tissue Tumors, 5th edition, 2008
Moosavi C, Jha P, Fanburg-Smith JC. An update on plexiform fibrohistiocytic tumor and addition of 66 new cases from the Armed Forces Institute of Pathology, in honor of Franz M. Enzinger, MD. Ann Diagn Pathol. 2007 Oct;11(5):313-9.
Remstein ED, Arndt CA, Nascimento AG. Plexiform fibrohistiocytic tumor: clinicopathologic analysis of 22 cases. Am J Surg Pathol. 1999 Jun;23(6):662-70.
Salomao DR, Nascimento AG. Plexiform fibrohistiocytic tumor with systemic metastases: a case report. Am J Surg Pathol. 1997 Apr;21(4):469-76.
Zelger B, Weinlich G, Steiner H, Zelger BG, Egarter-Vigl E. Dermal and subcutaneous variants of plexiform fibrohistiocytic tumor. Am J Surg Pathol. 1997 Feb;21(2):235-41.
Enzinger FM, Zhang RY. Plexiform fibrohistiocytic tumor presenting in children and young adults. An analysis of 65 cases. Am J Surg Pathol. 1988 Nov;12(11):818-26.
Billings SD, Folpe AL. Cutaneous and subcutaneous fibrohistiocytic tumors of intermediate malignancy: an update. Am J Dermatopathol. 2004 Apr;26(2):141-55.
Jaffer S, Ambrosini-Spaltro A, Mancini AM, Eusebi V, Rosai J. Neurothekeoma and plexiform fibrohistiocytic tumor: mere histologic resemblance or histogenetic relationship? Am J Surg Pathol. 2009 Jun;33(6):905-13.
