PF/PM lesions are poorly circumscribed masses which on histopathological microscopic analyses consist of bland fibroblastic and myofibroblastic spindle-shaped cells mixed with variable proportions of giant epithelioid ganglion cell-like cells. These cells are in a myxoid (i.e. a clear, mucus-like substance which when prepared using a standard H&E staining method appears more blue or purple than the red color of normal tissues) to fibrous (i.e. high collagen fiber content) background which may contain areas of necrosis (i.e. sites of dead cells). Overall, the cells in these lesions are amphophilic or basophilic, may have vacuole-laden cytoplasm, are slowly multiplying based on their<unk>  index, and lack atypical mitosis figures that might be suggestive of a malignancy. The presence of at least some giant epithelioid ganglion-like cells within this histopathological background are necessary and definitive evidence that a swelling or tumor is a PF/PM. Compared to adult cases, pediatric cases of PF/PM lesions are often better delineated from normal tissue, are more cellar, have a greater frequency of necrosis sites, contain diffuse sheets of epitheliod ganglion-like cell cells but lack a spindle-shaped cell component, and are lobulated. The spindle-shaped cells, but not epithelioid ganglion-like cell cells, in<unk><unk>  lesions express smooth muscle actin proteins.
Proliferative fasciitis and proliferative myositis
Interstitial granulomatous dermatitis with arthritis
Blistering distal dactylitis
Remitting seronegative symmetrical synovitis with pitting edema
Photosensitivity with HIV infection
Nodular fasciitis
Milia-like calcinosis
Villonodular synovitis