Folliculitis nuchae or acne keloidalis, is a scarring folliculitis producing a keloid-like mass. Its pathogenesis remains unclear, however, trauma, chronic irritation, seborrhea, infection and increased testosterone level are perceived as possible etiologies in affected individuals. The condition remains rare in females with only 2 case reports described. 

The first case describes a 36-year-old woman who reported a mass on her occiput for 2 years. Initially, the lesions appeared as tiny "bumps" that grew to become larger tumors. No previous history of a haircut was present. She didnt describe any form of trauma or experiencing irritation of the scalp. She reported a hair straightened procedure by perming and tried diverse creams at the early stages of the lesions without any improvement. No history of menstrual irregularities was revealed. 

Examination showed a healthy woman without virilization, with a hairless, fibrotic mass at the nape of the neck, which indicated the diagnosis of acne keloidalis. She was advised of surgical extirpation but refused to go on with the procedure. 

The second case described a case of a 30-year-old Nigerian female who presented with a growth in the occiput that appeared 6 months ago and had increased in size in the last 2 months before presentation. The patient was 2 months pregnant and described no irregularities in menstrual history before the pregnancy. She gave a history of treatment for atopic dermatitis and keratoconjunctivitis about 17 years ago. It was her second pregnancy, with no previous abortions. 

Examination revealed a healthy-looking female without evidence of virilization, with ice peak scars and post-inflammatory hyperpigmentation from previous acne. Greasy scales on the scalp were seen as suggestive of seborrheic dermatitis. A lobulated mass with a diameter of about 8 cm on the occiput which was firm to touch and hairless. Rest systems were normal. 

Source: Ogunbiyi A, George A. Acne keloidalis in females: case report and review of literature. J Natl Med Assoc. 2005;97(5):736-8.