Positron emission tomography in laryngeal cancer.In previous studies, positive electron tomography (PET) measuring uptake of 18F-fluoro-2-deoxyglucose has differentiated between benign and malignant lesions using standardized uptake values (SUV), lesion-to-normal liver background ratio of radioactivity, or glucose quantification. Areas with high rates of glucose utilization have increased uptake. Accuracy to differentiate benign and malignant lung lesions is reportedly 87-94% and for laryngeal lesions 82-88%. A 61-yo male presented with complaints of alopecia alopecia (ăl'əpē`shēə): see baldness. and 25-lb weight loss over the last year. Labs revealed polycythemia polycythemia (pŏl'ēsīthē`mēə), condition characterized by an increase in the production of red blood cells, or erythrocytes, in the blood. , hemoglobin 17.8 and hematocrit 52.8. Chest x-ray showed a left upper lobe lesion. CT confirmed left lung lesion measuring (4.5 X 6 cm) and a right upper lobe lesion measuring (2.5 X 4 cm). Lung cancer was suspected because of the history of smoking. An ear, nose, and throat test revealed a fixed mass over the right true vocal cord true vocal cord n. See vocal cord. true vocal cord Anatomy A fold of laryngeal mucous membrane that produces sound when taut and vibrating . Subsequent biopsies of the laryngeal lesion were positive for invasive squamous cell carcinoma squamous cell carcinoma n. A carcinoma that arises from squamous epithelium and is the most common form of skin cancer. Also called cancroid, epidermoid carcinoma. . Whole body PET scan revealed multiple areas of increased uptake in the left lung, right apex and inferior laryngeal region consistent with malignancy. At diagnosis, the laryngeal lesion had a maximum SUV of 20 (mean, 8), while the index lung lesion had a maximum SUV of 10 (mean, 4). CT guided biopsy of an index lung lesion stained positive for acid fast bacilli with caseating granulomas, which was diagnosed Mycobacterium avium intracellulare Mycobacterium avium intracellulare is an atypical mycobacterial infection which can occur in the later stages of AIDS. It can also affect women who do not have AIDS and usually first presents as a persistent cough. (MAI) complex. Treatment for MAI included clarithromycin, ethambutol ethambutol /etham·bu·tol/ (e-tham´bu-tol) an antibacterial, specifically effective against Mycobacterium; used with one or more other antituberculous drugs in the treatment of pulmonary tuberculosis, administered as the , and rifampin rifampin (rĭfăm`pĭn), antibiotic used in the treatment of tuberculosis. It is also used to eliminate the meningococcus microorganism from carriers and to treat leprosy, or Hansen's disease. and for laryngeal cancer cisplatin and radiotherapy. A PET scan 5 months after treatment ended showed the laryngeal lesion had minimal uptake and normal SUVs, while the index lung lesion had a maximum SUV of 11 (mean, 5). PET imaging has limitations in differentiating acute infectious processes and malignancies, despite the belief that PET scans are accurate. Biopsies are important to diagnose the underlying process causing increased glucose metabolism. J.F. Watkins III, MD, O. Nachar, MD, PhD, and D.N. Oubre, MD. Ochsner Clinic Foundation, New Orleans, LA. |
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