Surgical Pathology Criteria–

Nodular Fasciitis

Differential Diagnosis

Proliferative Fasciitis Nodular Fasciitis
Ganglion-like cells present No ganglion-like cells
Clusters or linear arrangement of small vessels Vessels usually not clustered

 

Proliferative Myositis Nodular Fasciitis
Ganglion-like cells present No ganglion-like cells
No damage to muscle fibers resulting in a checkerboard pattern with lesional cells between patches of intact muscle Muscle fibers obliterated or damaged
Nodular fasciitis may occasionally involve muscle

 

Sarcomas (General) Nodular Fasciitis
Usually over 4 cm Rare over 5 cm
Frequent cellular pleomorphism No pleomorphism
Atypical mitotic figures common Atypical mitotic figures rare
Coarse, granular, irregular chromatin Fine, pale, even chromatin

 

Nodular Fasciitis Low Grade Fibromyxoid Sarcoma
Usually superficial Usually deep soft tissues
S and C shaped bundleslll of cells Alternating fibrous and myxoid areas with whorling
Small Usually large
Essentially never metastasizes Metastatic rate reported from 6-60%, probably closer to 10%
LGFS may contain areas indistinguishable from nodular fasciitis; both are composed of bland cells

 

Inflammatory Myofibroblastic Tumor Nodular Fasciitis
Frequently over 5 cm Rarely over 5 cm
Usually in children Rare in children
Frequently involves abdominal cavity Does not involve abdominal cavity
Variable patterns Usually loose pattern throughout
Prominent inflammatory cells Only scattered inflammatory cells

 

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 Nodular Fasciitis, Hyalinized
Paucicellular Moderately cellular areas
No mucin Cystic mucin pools, tissue tears
Lacks S and C shaped bundles of cells S and C shaped bundles of cells
Mitotic figures absent or rare Mitotic figures may be numerous

 

Myositis Ossificans Nodular Fasciitis
Always involves muscle May involve muscle
Zonal osteoid and bone Focal bone formation

 

Intramuscular Myxoma Nodular Fasciitis
Very hypocellular Moderately cellular
No grouping of cells Undulating bundles of cells
No tissue culture appearance Tissue culture appearance with tears and spaces in tissue
Rare mitotic figures Frequent mitotic figures

 

Juxta-articular Myxoma Nodular Fasciitis
No grouping of cells Undulating bundles of cells
No tissue culture appearance Tissue culture appearance with tears and spaces in tissue
Rare mitotic figures Frequent mitotic figures

 

Inclusion Body Fibromatosis Nodular Fasciitis
Vast majority very young Uncommon in children
Vast majority in hands and feet Rare in hands and feet
Inclusions No inclusions

 

Benign Myxoid Nerve Sheath Tumors Nodular Fasciitis
Mitotic figures rare Mitotic figures frequent
S100 essentially always positive S100 negative

 

Plexiform Fibrohistiocytic Tumor Nodular Fasciitis
More mature collagenous stroma Loose, immature stroma
Small, dense nuclei Vesicular nuclei
Mitotic figures usually rare Mitotic figures frequent
Nodules of histiocytes frequent Foam cells and histiocytes infrequent
Plexiform rays of fibrous tissue Loose C and S shaped bundles of cells

 

Fibromatosis, Abdominal Desmoid and Extra-abdominal Desmoid Nodular Fasciitis
Usually dense collagenous stroma Collagenous stroma focal or rare
Linear fascicles of cells Undulating bundles of cells
Infrequent mitotic figures Frequent mitotic figures
Usually >3 cm Usually <4 cm
Beta-catenin 80-90% Beta-catenin negative

 

Nodular Fasciitis Myofibroma
Lacks biphasic pattern Biphasic nodular pattern
Lacks HPC-like vascular pattern Frequent HPC-like vascular pattern
Multiple lesions rare 25% of cases multifocal
Desmin variable Desmin negative

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