Correlation Between Ultra-High Frequency Ultrasound (UHFUS) and Histological Features of Typical Lesions in Hidradenitis Suppurativa.

Objectives: Hidradenitis suppurativa (HS) is a chronic inflammatory disease affecting hair follicles, significantly impacting patients' quality of life. While clinical assessment remains the cornerstone of diagnosis and staging, ultrasound (US) has emerged as a valuable tool for disease evaluation, treatment guidance, and monitoring. The introduction of ultra-high frequency ultrasound (UHFUS) allowed for near in vivo histopathological examination of HS lesions. This study aimed to correlate UHFUS features with histopathological findings in HS lesions.

Methods: Three patients at different disease stages underwent pre-surgical UHFUS mapping using a 70 MHz linear probe. Regions of interest (ROIs) were identified and marked preoperatively. Patient 1 had an abscess and perilesional skin, Patient 2 had a draining abscess, and Patient 3 had a clinically evident tunnel. Local excision was performed for Patient 1, while wide excision was conducted for Patients 2 and 3. Tissue samples underwent histological examination, and UHFUS findings were analyzed by three independent observers in consultation with a pathology expert.

Results: UHFUS demonstrated the ability to delineate fluid collections, tunnels, and subclinical lesions with high precision. Case 1 revealed a fluid collection with an intra-lesional drop-shaped inclusion, corresponding histologically to a neutrophilic abscess with keratin-filled cysts. Case 2 showed an elongated inclusion within a fluid collection, which histology confirmed as a keratin cyst linked to a tunnel. Case 3 exhibited a tunnel structure characterized by hyperechoic bands on UHFUS, correlating histologically with a keratinized epithelial-lined tunnel.

Conclusions: These findings highlight UHFUS as a non-invasive tool enhancing HS assessment, bridging clinical and histopathological evaluation. Further research is needed to standardize parameters and optimize its clinical utility.