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nodular fasciitis (pseudosarcomatous fasciitis)
Epidemiology:
- common among soft tissue mass lesions
- all age groups, most often young adults
Pathology:
- usually subcutaneous, may be intramuscular
- upper extremities, trunk, head & neck most frequently affected
- intravascular fasciitis - extends into vessel lumen
- cranial fasciitis - involves skull
Microscopic Pathology:
- plump, uniform fibroblastic/myofibroblastic cells
- may be highly cellular
- sometimes storiform pattern
- typically some loose or tissue culture like pattern
- lacks nuclear hyperchromasia or pleomorphism
- usually little collagen, but may have focal keloid-like collagen bundles
- mitoses may be plentiful, but are not atypical
- extravasated red cells, chronic inflammatory cells and multinucleated osteoclast-like giant cells common
- border of tumor typically infiltrative, at least focally
- occasionally osseous metaplasia seen
Immunohistochemistry:
- SMA, MSA usually positive
- desmin rarely positive
- keratin, S100 negative
- CD68 + osteoclast-like giant cells & occasional spindle cell
Clinical manifestations:
- rapidly growing, most cases ~1-2 months prior to surgery
- soreness or tenderness
- almost always < 5 cm, (usually < 2 cm.)
- some report previous trauma at site
- recurrence after excision rare, similar for cranial fasciitis and intravascular fasciitis
General
benign fibroblastic/myofibroblastic neoplasm
References
- WHO Classification Tumours of Soft Tissue and Bone
Fletcher, Unni & Mertens Eds. IARC Press 2002