Hidradenitis Suppurativa Mimicking Tuberculosis Scrofuloderma: The Role of Dermatologic Ultrasound as a Diagnostic Tool.

Hidradenitis suppurativa (HS) is a chronic inflammatory disease of the apocrine glands, typically presenting with cycles of flare-ups and periods of improvement. It predominantly affects women and is commonly found in areas such as the axillae, inguinal, and inframammary regions. We present a case of a 25-year-old male from Brazil who presented with recurrent cervical lesions over two years, initially suspected to be skin tuberculosis (scrofuloderma). Diagnostic workup included polymerase chain reaction (PCR), tuberculin skin test (TST), chest X-ray, and histological analysis, all of which ruled out infectious causes. High-frequency dermatological ultrasound revealed tortuous fistulous tracts with hyperechoic fragments in the dermis and subcutaneous tissue, suggesting HS. A subsequent biopsy confirmed the diagnosis of HS, with histopathological findings of perifollicular lymphocytic infiltration. The patient's clinical progression and the development of a new lesion in the right axilla further supported the diagnosis. This case highlights the importance of ultrasound as an adjunctive tool in diagnosing atypical HS presentations and differentiating it from other conditions such as scrofuloderma. It also emphasizes the necessity of considering non-intertriginous areas when diagnosing HS and the need for a comprehensive diagnostic approach, including imaging and biopsy, to exclude other diseases.