Clinical utility of 18 Fluorodeoxyglucose (FDG)-PET/CT scans in patients with suspect ocular tuberculosis
A 38-year-old female patient presented with a history of recurrent attacks of bilateral pain, redness, and visual loss since the past 2 years. Previous investigations included a complete blood count and a mantoux test, and had 1 month ago, been started on empirical antitubercular therapy (based on a “positive” result) along with topical corticosteroid therapy.\nHer best corrected visual acuity was counting fingers at 2 meters in the right eye and counting fingers close to her face in her left eye. Slit lamp examination of her right eye revealed fresh nongranulomatous keratic precipitates with a severe anterior chamber reaction (cells 2+, flare 2+). The anterior chamber was shallow with 360 ° adherence of the iris to the capsule of a complicated cataract. There was significant forward bowing of the iris diaphragm with peripheral anterior synechiae. There was significant iris neovascularization seen. Similar findings were seen in the left eye but there was a more marked shallowing of the anterior chamber with extensive irido-corneal touch. There was no fundal view but an ultrasound showed an anatomically normal posterior segment. The intraocular pressure was 10 and 8 mmHg.\nA repeat mantoux test showed induration of 21×18 mm. Her total and differential blood counts, tests for serum creatinine, serum calcium, serum angiotensin converting enzyme, and serological tests to detect HIV infection were normal.\nA 18 FDG-PET scan revealed a metabolically active, large 3×2.2 cm heterogenous right supraclavicular, partially necrotic, lymph node (SUV max 6.6) [Figure , ]. There were metabolically active lymph nodes in the chest (right paratracheal [1.0×1.5 cm; SUV max 5.5] and subcarinal [1.5 × 2.6 cm; SUV max 7.7]) but the lungs were clear. Minimally metabolically active nodes were seen in the axilla.\nShe underwent ultrasound guided fine needle aspiration cytology of the right cervical lymph node that was highlighted on the PET/CT scan. The microscopic examination revealed caseating granulomas suggestive of tuberculosis. A Transcription Mediated Amplification (TMA) polymerase chain reaction (PCR) for mycobacterium tuberculosis genome had a positive result.\nShe was started on a standard four drug antitubercular regimen along with topical and periocular steroid therapy. On last follow up one month later there was a marked reduction of clinical anterior chamber activity.