Folliculitis keloidalis nuchae is associated with the risk for bleeding from haircuts

Folliculitis keloidalis nuchae (FKN), characterized by nucheal pimples and keloids, has a predilection for curly African hair. The disease is 10 times more common in males than females. The aim of this study was to investigate determinants of FKN in males.

Factors associated with the presence of FKN were investigated from two cross-sectional studies involving 1042 children and 874 adults, respectively. All participants had given informed consent. A clinical diagnosis of FKN was made only if nucheal keloidal papules (or plaques) were present. Multiple logistic regression was used to assess the relationship between FKN and specific characteristics in male participants.

The odds ratio (OR) for FKN in males was higher in the adult than the child study [OR = 7.26, 95% confidence interval (CI) 3.13-16.88; P < 0.0001]. The OR in the group aged <25 years was similar to that in the group aged >50 years (OR = 2.44, 95% CI 0.75-7.89; P = 0.14) but significantly higher in those aged >25-50 years (OR = 5.75, 95% CI 2.67-12.64; P < 0.0001), which is inconsistent with inherent degenerative disease (in which the OR would be expected to increase or remain constant) and may correspond to the current popularity of closely shaven hairstyles. Most hair (86%) was cut close to the scalp with clippers, a process often accompanied by the exhibition of symptoms. For example, 47% of respondents reported transient haircut-related crusts or pimples (Yes vs. No, FKN OR = 3.44, 95% CI 1.43-8.301; P = 0.006), and 32% of adult males reported at least one episode of bleeding (Yes vs. Never, FKN OR = 3.45, 95% CI 1.23-9.68; P < 0.019).

Prospective studies are needed to clarify the extent to which mechanical haircut-associated injuries cause or are the result of FKN. Haircut-associated bleeding raises concern about the potential transmission of blood-borne infections.