Scalp Apocrine Glands: The Neglected Component of the Hair Follicle Complex

In humans, apocrine glands are generally associated with chemical signaling and body odor. Their presence in the scalp is poorly documented, commonly being associated with benign and malignant tumors. If apocrine glands are consistently present in the normal scalp or become apparent only under pathological circumstances remains unclear. Moreover, their potential physiological role in relation to the hair follicle and microbiome modulation has yet to be fully elucidated.

The role of scalp apocrine glands is often considered rudimentary and may be underestimated. However, the higher excretions of urea and potassium compared to eccrine glands suggest a potential role in the removal of metabolic waste products and electrolyte balance. Additionally, the openings of apocrine ducts drain into the hair follicle, mixing with follicular contents and sebum before reaching the skin's surface. This highlights a possible close interaction between the apocrine glands and microbiome. Furthermore, given the anatomical and functional association between follicular units and apocrine glands, it is likely that they participate in the pathogenesis of follicular occlusion diseases.

This article aimed to review existing research on scalp apocrine glands, clarifying this underexplored topic and highlighting them as a potentially relevant component of scalp physiology and pathology.