Oral Chronic Ulcerative Stomatitis and Cutaneous Leprosy Diagnosis and Management

Conclusions

• Chronic ulcerative stomatitis should be considered when oral erosions clinically resemble erosive lichen planus but direct immunofluorescence shows speckled nuclear IgG in basal and parabasal keratinocytes.
• Direct immunofluorescence is key to distinguishing chronic ulcerative stomatitis from oral lichen planus, and recognizing it may shift treatment toward hydroxychloroquine rather than escalating immunosuppression.
• Granulomatous dermatitis with histiocytes, macrophages, plasma cells, and lymphocytes should prompt further testing for leprosy, with Fite stain being the most useful next step.
• A negative AFB stain does not reliably exclude leprosy, so a Fite stain is preferred when leprosy is in the differential.
• Some seemingly atypical leprosy cases in the United States may be linked to zoonotic or environmental exposure rather than classic travel or armadillo contact alone.
• Amoebae may serve as an environmental reservoir that helps M. leprae persist and may facilitate transmission through inhalation or percutaneous inoculation.
• Genetic background, especially immune recognition and cytokine-pathway variants, likely influences susceptibility to leprosy and its clinical behavior.
• The leprosy bacillus can persist in a viable state despite treatment, so recurrent lesions after therapy do not necessarily mean reinfection or drug resistance.
• Reggressing leprosy can present as small residual plaques after treatment and may be mistaken for persistent active disease.
• Modern molecular viability assays can help distinguish current viable leprosy from historical or regressing bacilli more quickly than traditional mouse footpad testing.
• Dermatologists should maintain a higher index of suspicion for leprosy and related mimickers because delayed recognition can leave limited therapeutic options once nerve damage or advanced disease occurs.