If lymphangitic spread has occurred, other nodules of a similar size and appearance will be located proximally to the initial lesion, occasionally connected by a faint erythematous streak. Lymphadenopathy may be present. Advanced lesions as witnessed in disseminated cases may ulcerate and become necrotic. Synovial involvement will reveal a tender, erythematous swollen joint. Individuals who are consistently exposed to the organism are more likely to develop the infection.
Immunocompromised hosts are also at an increased risk.
Mycobacterial culture must be performed at 32 C. Positive results typically take 4-6 weeks. Biopsy for histopathology from cutaneous lesions or from intra-articular tissue. The histopathology varies depending on the duration of the lesion biopsied. Lesions less than 3 months old show a nonspecific mixed inflammatory infiltrate, but acid-fast stains will typically reveal bacilli. By 6 months, lesions display characteristic tuberculoid granulomas, often containing a stellate abscess.