Imaging granulomatous lesions with optical coherence tomography.

Area of Science:

• Dermatology
• Ophthalmology
• Medical Imaging

Background:

• Optical coherence tomography (OCT) is an imaging technique used to visualize tissue microstructure.
• Understanding OCT characteristics of granulomatous lesions is crucial for diagnosis and comparison with nonmelanoma skin tumors.
• Previous studies have established OCT features for various skin tumors.

Observation:

• This study examined two patients with granulomas: one with tophi and another with granuloma annulare (GA).
• Digital photography, OCT imaging, and biopsy were performed for each lesion.
• OCT images were compared with histological findings and OCT images of nonmelanoma skin tumors.

Findings:

• OCT of tophi revealed hyperreflective, rounded, cloud-like structures with a hyporeflective fringe, obscuring deeper dermis due to urate crystals.
• OCT of GA showed distinct patterns: a hyporeflective rounded structure and a lobulated, wing-like structure.
• Granulomatous tissue appeared as hyporeflective areas, while urate crystals were hyperreflective.

Implications:

• OCT can differentiate granulomatous lesions, with urate crystals appearing reflective and granulomatous tissue absorbent.
• A novel 'wing-like' OCT pattern was observed in GA, potentially representing diffuse GA or lymphocytic infiltrate.
• Further research is needed to determine the specificity and sensitivity of these OCT patterns for granulomatous diseases.