Lymph nodes in hidradenitis suppurativa.

BACKGROUND: Hidradenitis suppurativa (HS) is an inflammatory disease, and yet palpable lymph nodes are rarely found. This may be due to lack of lymph node swelling or to the inability to palpate lymph node regions due to overlying disease. Ultrasound was used to identify and measure regional lymph nodes in HS patients. METHODS: High-resolution ultrasound scanning was carried out with compact linear 15-7 MHz and linear 12-5 MHz probes in both axillae and inguinal regions following informed consent. RESULTS: A total of 198 lymph nodes were identified in 6 HS patients in Hurley stage II and 4 in stage III, and 101 from regional control scans in healthy controls. All the lymph nodes in both HS patients and controls showed a normal oval shape, with a hypoechoic rim and a hyperechoic center, and all were located in the deep subcutaneous tissue. The overall mean lymph node number per region was not significantly different. The overall mean lymph node diameter was not significantly different, but in patients with Hurley stage III disease it was significantly increased (1.3 +/- 0.4 cm, p = 0.03). CONCLUSION: Lymph node involvement only occurs with late-stage HS and may therefore reflect secondary infection rather than primary etiological involvement.