TLDR Immunohistochemistry helps accurately identify and differentiate malignant trichilemmoma.
The study explored the histologic and immunohistochemical features of trichilemmoma and its malignant counterpart, malignant trichilemmoma (mTr), which are tumors differentiating into the outer root sheath (ORS) of hair follicles. It was found that the presence of clear cells, glycogen-containing cells, and trichilemmal keratinization were not exclusive to these tumors, as similar features were observed in Bowen's disease. However, immunohistochemical analysis revealed that trichilemmoma and mTr shared similar immunophenotypes with the ORS, particularly in the lower hair follicle, characterized by specific keratin and involucrin expression. This suggested that immunohistochemistry could be a valuable tool for accurately identifying and differentiating mTr, prompting a reevaluation of previous mTr diagnoses using these techniques.
9 citations
,
July 2008 in “Archives of Dermatological Research” 276 citations
,
January 2005 in “International review of cytology” The document reviewed the genomic organization and expression characteristics of human hair keratin genes, highlighting their role in hair follicle biology and hereditary disorders. It noted that research on human hair keratins lagged behind studies in other species. The review discussed the complex regulatory mechanisms of hair keratin expression and the differentiation of hair follicle compartments. It also addressed keratin-related pathologies, such as epidermolysis bullosa simplex and pachyonychia congenita, which affect the outer root sheath and nail beds, respectively. The study emphasized the need for further research to understand the molecular mechanisms governing hair follicle differentiation and keratin expression.
199 citations
,
January 2004 in “The International Journal of Developmental Biology” Hair follicle growth and development are controlled by specific genes and molecular signals.
29 citations
,
April 2003 in “Experimental dermatology” Human hair follicles grown in vitro maintain normal keratin patterns and structure.
10 citations
,
October 2000 in “PubMed” 
94 citations
,
February 1994 in “The journal of investigative dermatology/Journal of investigative dermatology” EGF makes hair follicles grow longer but stops hair production.
135 citations
,
November 1987 in “Differentiation”
