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

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.

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.

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.

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.