Laryngeal Sarcoidosis Diagnosed by PET/CT Through Inflammatory Activity

A new study revealed that imaging techniques such as positron-emission tomography (PET)/computed tomography (CT) can detect laryngeal inflammation in sarcoidosis patients, allowing the diagnosis of laryngeal sarcoidosis.

The conclusion was made based on a case report of laryngeal sarcoidosis in a study titled “An atypical sarcoidosis involvement in FDG PET/CT“ published in the journal Medicine.

Laryngeal involvement in sarcoidosis is very rare — it’s detected in 0.5 percent to 1 percent of patients — and difficult to diagnose. Doctors need to exclude cancer and other diseases that cause inflammatory foci, known as granulomas, in the larynx. The diagnosis requires confirmation by several other examinations, such as blood tests and electrocardiograms.

The study reports the case of a 63-year-old man with speaking problems (dysphonia) who showed laryngeal lesions that looked suspicious for cancer after a laryngoscopy to exam his larynx and vocal cords.

The patient had a PET/CT, a nuclear medicine imaging examination, and doctors detected the accumulation of 18F-Fluorodesoxyglucose (FDG) in a right vocal cord and local lymph nodes. FDG, a radiolabeled sugar (glucose) molecule, accumulates in several types of tumors, which are metabolically more active than healthy tissue. This allows clinicians to discriminate between the two types of tissues.

Normally, doctors do an FDG PET/CT examination to localize and diagnose several malignancies in patients. However, in this patient, doctors used the same imaging technique to detect increased metabolic activity by the laryngeal granulomas.

“Previous studies have shown that FDG PET/CT can be used to accurately assess inflammatory activity in patients with persistent symptoms without biological inflammatory activity, especially in uncommon localizations or when a biopsy is not possible,” the authors wrote in their report.

Doctors looked at the patient’s laryngeal biopsy sample and found granulomas typical of sarcoidosis while they excluded infectious diseases or tumors. After six months of steroid treatment, the patient underwent another FDG PET/CT to assess therapeutic efficacy. This time, doctors found a significant decrease of the abnormal FDG uptake in the right vocal cord, and they further confirmed that the lesion was benign.

This patient’s case demonstrates that FDG PET/CT can detect inflammatory activity typical of rare laryngeal sarcoidosis. Importantly, the same type of imaging technique can assess therapeutic effectiveness over time. If extended to other patients, FDG PET/CT could help improve the diagnosis of laryngeal sarcoidosis.