Cervical Tuberculous Lymphadenitis Associated With New-Onset Acanthosis Nigricans Following Antitubercular Therapy: A Case Report.

Cervical tuberculous lymphadenitis (CTL), also known as scrofula, is an extrapulmonary manifestation of tuberculosis, a disease that is endemic to many developing countries, particularly Sub-Saharan Africa and Asia, but may also be found worldwide in developed countries like the United States. CTL can be difficult to detect and may mimic other similar-appearing conditions, so a high index of suspicion is required to accurately diagnose the condition when a patient presents with one or more neck masses. Incision and drainage and excisional surgery are aggressive options available to treat CTL but are not preferred due to a high risk of serious adverse events like fistulization and hematological dissemination. Clinicians typically opt for traditional tubercular RIPE (rifampin, isoniazid, pyrazinamide, and ethambutol) therapy for its high efficacy in treating extrapulmonary tuberculosis. Despite this preference, RIPE therapy has been known to elicit a myriad of side effects that demand close monitoring by clinicians. One side effect of the RIPE regimen that has yet to be reported is acanthosis nigricans (AN), a dermatological sign that presents as thickening and darkening of the skin, often in intertriginous areas. AN frequently occurs in conjunction with insulin resistance, and interestingly, the RIPE drug isoniazid has been implicated in insulin derangements in patients, most notably diabetics. However, the incidence of AN secondary to isoniazid use has not been explicitly recorded in the literature to date. Herein we present a novel case of a young man from Nepal with CTL treated via RIPE therapy who developed AN likely secondary to isoniazid use.