Background: Alopecic and aseptic nodules of the scalp (AANS) is a new entity reported first in Japan as ‘pseudocyst of the scalp’. Only retrospective studies have been published. Objectives: To describe the clinicopathological features of AANS (pseudocyst), to evaluate the response to doxycycline and to compare the results to those obtained from patients with dissecting cellulitis of the scalp (DCS). Methods: Fifteen patients with AANS and 7 with DCS were prospectively included. A puncture and a biopsy were made. Patients were treated with doxycycline (100 mg/day) for 3 months. Results: AANS affects predominantly young (mean age 29.7 years), Caucasian (11/15), male (14/15) patients. The main location of the nodules was the occiput. The associated alopecia was nonscarring. Material from the puncture was aseptic. The histopathology showed a deep granuloma in 7 of 14 patients and a nonspecific inflammation in 7 patients. After 3 months, 8 patients were cured and 3 had a good response. Conclusions: The singular aspect of the nodules, the nonscarring alopecia, the deep inflammatory infiltrate and the efficacy of doxycycline confer specificity to AANS.