Follicular Pathology
Big topic but put simply if a follicle ruptures you get surrounding granulomas. Collections of neutrophils suggest a bacterial folliculitis. Follicular plugging suggests lupus erythematosus or lichen sclerosus. Clear cells in the follicular epithelium suggests follicular mucinosis. Spread of melanocytes down a follicle suggests Lentigo maligna and if atypical keratinocytes then Bowen's disease is the likely diagnosis. Ocassionally unusual things such as Mollusca can be found in follicles. Follicular variants of T cell lymphoma may also be seen.
Darier's disease and Pityriasis rubra pilaris are based around follicles
Follicular derived tumours are numerous and include Trichoepithelioma, Trichilemmoma, Pilomatricoma, Proliferating Trichilemmal cyst, Fibrofolliculoma, Trichodiscoma and Trichoblastoma. Some of these tumours are associated with the Birt Hogg Dube syndrome and renal carcinomas.
