Fibromatosis

4-6% of Caucasian adults > 50 years of age

• Deep fibromatosis

2.40-4.43 new cases per 100,000 persons/year

• Recurrences common for both superficial and deep fibromatoses, but deaths only from deep fibromatoses

• Increased incidence in familial adenomatous polyposis

Microscopic

• Sweeping fascicles of myofibroblasts

• Smooth nuclear membranes and small nucleoli in most cells

• Occasional cells with stellate cytoplasmic contours

• Occasional foci with storiform pattern similar to nodular fasciitis

• Some cases show keloid-like collagen

• Small but conspicuous vessels

• Gaping, thin-walled vessels with perivascular sclerosis often feature of mesenteric fibromatosis

Ancillary Tests

• β-catenin (+) (nuclear), especially in deep lesions, SMA(+); desmin (-), keratins (-), CD117(+/-)

Top Differential Diagnoses

• Scar

• Tenosynovial giant cell tumor (giant cell tumor of tendon sheath, pigmented villonodular tenosynovitis)

• Leiomyoma and leiomyosarcoma

• Clear cell sarcoma

• Epithelioid sarcoma

• Low-grade fibromyxoid sarcoma

Fibromatosis, Clinical Image
This fibromatosis is unusually superficial and arose in the chest wall of a young adult. These tumors are typically deep (deep fascia or within muscle).

Fibromatosis, Low Magnification
This image of a deep-type fibromatosis shows sweeping fascicles of spindle cells separated by regularly spaced collagen. Even at this magnification, small vessels are readily apparent .

Fibromatosis, Gross Specimen
This gross photograph shows a large, deep fibromatosis of the shoulder that has eroded into the scapula. Superficial portions of such lesions can be encountered on skin biopsies.

Fibromatosis, Neck
This radiologic image shows a large fibromatosis of the head and neck in an elderly alcoholic man. Although more arise in the shoulder girdles (or in the abdominal wall in young women), the head and neck is a common location for fibromatoses.

TERMINOLOGY

Synonyms

• Deep fibromatosis: Aggressive fibromatosis, desmoid tumor

• Superficial fibromatoses: Palmar fibromatosis (Dupuytren contracture, Dupuytren disease), plantar fibromatosis (Ledderhose disease), penile fibromatosis (Peyronie disease), knuckle pads

Definitions

• Palmar fibromatosis: Nodular myofibroblastic proliferation of volar surface of hand that is prone to local persistence but does not metastasize

• Plantar fibromatosis: Nodular myofibroblastic proliferation of plantar surface of foot that is prone to local persistence but does not metastasize

• Peyronie disease: Penile fibrous lesion causing various deformities; initially pain with erection, erectile dysfunction

• Knuckle pads: Well-circumscribed thickening of skin over metacarpophalangeal and, more commonly, proximal interphalangeal joints

• Deep fibromatosis: Myofibroblastic proliferation of deep soft tissues with infiltrative growth pattern; prone to local recurrences but does not metastasize