Case Number : Case 4169 - 12 January 2023 Posted By: Saleem Taibjee

? Psoriatic alopecia. 

The transverse section shows 10 follicles out of which 4 are miniaturized. The basal layer of the epidermis is pigmented and the follicles seen in vertical section are curved suggesting that the patient has curly hair. The total number of follicles is reduced. There are virtually no sebaceous glands. The dermal collagen is thickened and hyalinized. Remnants of arrector pilorum are seen on the right side of two follicles in the last image . I think that this is a co-existent female pattern alopecia and scarring alopecia due to morphea or pseudopelade. Clinical picture, if available will be more useful in diagnosis.

Not sure. To me there appears to be fibrosing / cictaricial pattern but no significant active lichenoid pathology. I would consider frontal fibrosing alopecia and fibrosing alopecia in a pattern distribution. Although, typically psoriasis shows non-cicatricial alopecia, rare case of cicatricial alopecia has been reported, but don't find a very conclusive evidence of psoriasis. 

Scarring alopecia with some lymphocytic inflammation and no definitive interface change. The horizontal sections have a hint of premature desquamation of inner root sheath (PDIRS). No epidermal changes or peri-adnexal inflammation. Eccrine coils are sitting quite high in the dermis, a sign of retraction/scarring. No deep inflammation or dermal mucin. DDx: Later stage LPP/FFA, CCCA, less likely lupus. 

These are all good suggestions. However, the distortion of shape and orientation of the follicles in the transverse sections is what particularly caught my attention in this case. Catherine Stefanato has previously referred to this as the 'Z' sign. I can't easily find it in the textbooks or medical literature. It may indicate a mechanical cause i.e. traction alopecia. This is most evident in the image below.