A Diagnostic Challenge: A Case of Disseminated Nocardiosis Presenting With Generalized Lymphadenopathy in a Patient With Interleukin-12 Deficiency.

Deficiency in interleukin-12 (IL-12) can result in susceptibility to opportunistic infection, with IL-12 deficiency being a rare genetic cause. Nocardia farcinica is a gram-positive aerobic actinomycete that can cause disseminated and potentially lethal nocardiosis in immunocompromised patients. This report describes a 16-year-old male adolescent with IL-12 deficiency presenting with generalized lymphadenopathy due to disseminated Nocardia farcinica. The subject of our study is a male adolescent who exhibited clinical manifestations consistent with cholestasis. He underwent extensive workup for malignancy, suspecting cholangiocarcinoma initially. The workup turned out unremarkable, and later during his hospital stay, he deteriorated and required intensive care unit (ICU) admission, as he developed superior vena cava (SVC) syndrome from massive enlargement of mediastinal and cervical lymph nodes. During the patient's admission, it was found that he had a deficiency of interleukin-12 (IL-12). Later on, a blood culture revealed the presence of Nocardia farcinica species. Subsequently, the patient was initiated and improved drastically on an empirical antibiotic regimen consisting of amikacin, co-trimoxazole, meropenem, and moxifloxacin. Following that, the susceptibility results came out, and he was switched to oral co-trimoxazole and oral moxifloxacin as he no longer required inpatient care. This report highlights the importance of accurate diagnosis of causes of immunosuppression and early investigation, diagnosis, and management of potentially fatal opportunistic infections such as disseminated Nocardia farcinica.