Mycobacteria lentiflavum presenting as nasopharyngeal masses and nodular erythema: a case report

Abstract

Background: Mycobacterium lentiflavum, a slow-growing, primarily affects the lungs and cervical lymph nodes, with no reported involvement in the nasopharynx; this case report represents the first reported instance of mycobacteria lentiflavum involving the nasopharynx, accompanied by nodular erythema and other reactive rashes, which are clinically rare and prone to misdiagnosis. Case Presentation: A 35-year-old female presented with a history of "recurrent rhinorrhea and sensation of nasal foreign body, along with nodules on the extremities for more than 2 years". On examination, multiple tender nodules were observed on the lower limbs and dorsum of both hands without ulceration. The patient was positive for anti-γ-interferon antibody upon admission. A nasopharyngeal CT (computed tomography, CT) scan with contrast agent revealed the following: 1. Lesion in the right nasal cavity-right maxillary sinus-right ethmoid sinus, nature pending further investigation; 2. Inflammation in the right maxillary sinus and right frontal sinus. Biopsy of nodules on the lower limbs revealed nodular erythema. Pathological examination of the nasopharyngeal mass revealed granulomatous inflammation. Special staining included acid-fast staining (−), periodic acid-Schiff (PAS) staining (−), and next-generation sequencing (NGS) of nasopharyngeal mass tissue, which suggested Mycobacteria lentiflavum (sequence number 151). The final diagnosis was Mycobacteria lentiflavum infection in the nasopharynx. The nodular erythema was considered a reactive rash following Mycobacteria lentiflavum infection. After 3 months of treatment with clarithromycin, rifampicin, and moxifloxacin, symptoms in the nose and nodules on the extremities regressed, with no recurrence during follow-up. Conclusion: Mycobacterium lentiflavum infection is rare in clinical practice, and its clinical manifestations are nonspecific, especially when it involves the nasopharynx, making it even more uncommon, thus clinicians are prone to misdiagnosis.