Microscopic examination of skin in serial sections cut parallel to the surface often reveals peculiar and characteristic epithelial proliferations connected with the hair follicles. These so-called "bulge" growths (German: Wulst) are but rarely mentioned in the textbooks, despite the fact that they have been known for about 100 years. They are probably not so conspicuous in the scalp as on the trunk and neck and are more easily detected in "horizontal" than in vertical sections. Their function and significance are obscure.
At an early stage the fetal follicle shows two swellings of the outer root sheath, an upper one which is the anlage of the sebaceous gland and a lower one which by the Germans was called "der Wulst." Later in life, this bulge may disappear altogether or leave only insignificant remnants, or it may persist and develop into filaments and strands ending freely in the connective tissue. In the
MADSEN A. Studies on the "Bulge" (Wulst) in Superficial Basal Cell Epitheliomas. Arch Dermatol. 1964;89(5):698–708. doi:10.1001/archderm.1964.01590290064010
Coronavirus Resource Center
Customize your JAMA Network experience by selecting one or more topics from the list below.