CAUSES :
β’ Idiopathic (37-60%)
β’ Bacterial - streptococcal infections (most common cause in children), tuberculosis, leprosy, Yersinia enterocolitica, tularemia, Campylobacter, salmonella, Shigella, gonorrhea
β’ Sarcoid
β’ Drugs - sulfonamides, oral contraceptives, bromides, BARBITURATES, PENICILLIN
β’ Pregnancy
β’ Deep fungal - dermatophytes, coccidioidomycosis, histoplasmosis, blastomycosis
β’ Viral/chlamydial - infectious mononucleosis, lymphogranuloma venereum, paravaccinia
β’ Enteropathies - ulcerative colitis, Crohn disease
β’ Malignancies - lymphoma/leukemia, sarcoma, post radiation therapy
* BEHCETS SYNDROME
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DIFFERENTIAL DIAGNOSIS
β’ Superficial thrombophlebitis
β’ Cellulitis
β’ Septic emboli
β’ Erythema induratum (cold, ulcerating nodules on calves)
β’ Nodular vasculitis (warm, ulcerating nodules)
β’ Weber-Christian disease (violaceous, scarring nodules)
β’ Lupus panniculitis
β’ Cutaneous polyarteritis nodosa
β’ Sarcoidosis granulomata
β’ Cutaneous T cell lymphoma
β’ Erythema nodosum leprosum
β’ Elevated erythrocyte sedimentation rate
β’ CBC: mild leukocytosis
β’ Throat culture, ASO titers (throat culture usually not positive because infection typically resolves before lesions appear)
β’ Stool culture and leukocytes if indicated
β’ Skin testing for mycobacteria if indicated