Surgical Pathology Criteria–

Fibroma of Tendon Sheath

Differential Diagnosis

Tenosynovial Giant Cell Tumor Fibroma of Tendon Sheath
Oval histiocyte-like nuclei Elongate nuclei
Giant cells nearly always present Giant cells rare
Foamy histiocytes common Histiocytes rare
Hemosiderin common Hemosiderin rare
No slit-like vascular spaces Slit-like vascular spaces common
Smooth muscle actin negative Smooth muscle actin strong positive
Desmin may be positive Desmin negative

 

Fibroma of Tendon Sheath Inclusion Body Fibromatosis
Most common in adults Vast majority very young
Usually densely collagenized Usually cellular
No inclusions Inclusions usually present

 

Nodular Fasciitis Fibroma of Tendon Sheath
Rare on hands Most on hands
Rapid growth Slow growth
Not circumscribed Circumscribed
Virtually no recurrences May recur
Although fibroma of tendon sheath is typically sclerotic and nodular fasciitis is typically not, there is sufficient variation in patterns to cause overlap. Most such lesions on the hands are labeled fibroma of tendon sheath.

 

Desmoplastic Fibroblastoma Fibroma of Tendon Sheath
Wide distribution Most on hands or wrist
Single nodule Multilobular
Hypovascular Moderately vascular

 

Palmar or Plantar Fibromatosis Fibroma of Tendon Sheath
Usually located on tendon in palm or plantar surface Most commonly located on tendon of fingers
Cellular areas feature fascicles Cellular areas resemble nodular fasciitis

 

Knuckle Pads Fibroma of Tendon Sheath
Single nodule over any one joint Multinodular
Restricted to dorsal aspect of joints Located anywhere along tendon sheath

 

Benign Fibrous Histiocytoma Fibroma of Tendon Sheath
Rare in hands Common in hands
Histiocytes common Histiocytes rare
Giant cells common  Giant cells rare
Hemosiderin common  Hemosiderin rare
Smooth muscle actin may be scattered positive Smooth muscle actin strong positive

 

Cellular Fibroma of Tendon Sheath Adult or Infantile Fibrosarcoma
Common in hands Rare in hands in adults but may involve hands in infantile version
Rare >2 cm Frequently >4 cm
Cytologically bland Cytologically atypical
No atypical mitotic figures Atypical mitotic figures may be seen
Smooth muscle actin strongly positive Actin variable
Lacks t(12;15) t(12;15) present in most infantile cases

 

Cellular Fibroma of Tendon Sheath Synovial Sarcoma
Common in hands Rare in hands
Rare >2 cm Frequently >4 cm
Cytologically bland Cytologically atypical
No atypical mitotic figures Atypical mitotic figures may be seen
Smooth muscle actin strongly positive Actin negative
No SYT-SSX gene fusion SYT-SST gene fusion present

 

Fibroma of Tendon Sheath Calcifying Fibrous Pseudotumor
No calcification Calcification present
Inflammation uncommon Chronic inflammation present
Primarily located on digits Widely distributed
Slit-like vessels frequent Lacks slit-like vessels

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