Disorders of skin appendages

Chapter 15


Disorders of skin appendages




Non-inflammatory alopecia


Transverse (horizontal) sections are generally best for evaluation of non-inflammatory alopecia. Vertical sections may be used if serial ribbons of sections are cut from the block. A combination of vertical and transverse sections is always acceptable.




Pattern alopecia (androgenetic balding)




The essential histologic finding in pattern alopecia is progressive miniaturization of the follicular unit. This occurs predominantly in the central scalp, and in an asynchronous fashion. The biopsy will demonstrate variability in hair diameter. Focal spongiotic infundibulofolliculitis is common (mild seborrheic folliculitis). In long-standing cases, solar elastosis as well as elastotic degeneration of the fibrous tract remnants may be seen. Advanced pattern alopecia demonstrates a marked increase in vellus hairs (hair shaft diameter < inner root sheath diameter). Large sebaceous glands may be present, especially in males.






Inflammatory non-scarring alopecia


Either vertical or transverse (horizontal) sections may be used, but serial ribbons of sections should always be cut from the block. A combination of vertical and transverse sections is always acceptable.



Alopecia areata






The lymphocytes appear to target melanocytes within the hair bulb. White hairs are spared. The inflammation results in damage to the hair matrix, tapered hair shafts with fracture, and miniaturization of the follicular unit.






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Apr 26, 2016 | Posted by in Dermatology | Comments Off on Disorders of skin appendages

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