1956 Epstein W, Kligman AM

 
The pathogenesis of milia and benign tumors of the skin. J Invest Dermatol 1956;26:1–11 (Fig. 7).

View Figure  		Fig. 7   (orig. Fig. 11). Unusual vellus hair follicles important in the histogenesis of milia A, Two cords or buds of indifferent epithelial cells extend from the external root sheath of a vellus hair follicle cut obliquely in longitudinal section. The cords arise approximately at the site of normal sebaceous gland anlagen. B, Two hair follicles cut in cross section show that these abnormal anlagen grow out from the follicle and tend to surround it in a ring of indifferent epithelial cells and poorly differentiated sebaceous cells. C, This cross sectional view shows that the two cords don't always form a ring but may grow irregularly and without purpose. D, The two cords have joined to form a complete ring of indifferent epithelial cells about the hair follicle. Note also a very early milium originating in the ring. Actually, this picture is deceptive, because when reconstructed in three dimensions this ring turns out to be an apron of indifferent cells arising from the surrounding hair follicle.
 

Message

 
Vellus follicles often either lack sebaceous glands altogether or are formed imperfectly, showing transitions from undifferentiated epithelial buds to larger cords of undifferentiated cells with variable degrees of sebaceous differentiation or even none at all. These cords of epithelial cells represent abnormal anlage that grow out from the follicle and in cross section surround it as a ring. In three dimensions, this ring turns out to be an apron of undifferentiated cells.
 
Milia derive from the cords of epithelial cells.
 

Critique

 
The imperfectly formed sebaceous glands in the form of epithelial buds and cords that surround the follicle like an apron as described by Epstein and Kligman actually are mantles of Pinkus and collars of Zimmermann, i.e., normal structures continuous with normal follicles.
 
Mantles do not give rise to milia. The cystic structures pictured by Epstein and Kligman and referred to by them as milia are really sebaceous ducts within a mantle undergoing differentiation. Milia are cysts that form as a consequence of dilation of preexisting infundibula.
 
Herman Pinkus, the son of Felix Pinkus, following the presentation of this paper by Epstein and Kligman, commented to the effect that his father had described the mantle as an atrophic sebaceous gland and that he, himself, was pleased to learn from Epstein and Kligman that mantles were responsible for milia. In fact, Felix Pinkus regarded the mantle as a source of sebaceous cells, and milia as wholly unrelated to mantles.