No particular lab or imaging diagnostics
Deep skin biopsy, including dermis, subQ fat, fascia
Nephrogenic systemic fibrosis
Scleroderma, morphea
Goodpasture syndrome
Calciphylaxis, which may coexist
Eosinophilic granulomatosis with polyangiitis
Cellulitis
Granulomatosis with polyangiitis
Necrotizing fasciitis