Histologic Diagnosis of Inflammatory Skin Diseases

Hair Follicles

…at in follicles during the involutional phase of their cycle (catagen) when an appearance indistinguishable from that of isthmic epithelium is assumed by them. That epithelium, both of the isthmus and a follicle well advanced in catagen, is character…

Histologic Diagnosis of Inflammatory Skin Diseases

Images

…Foreign body reaction to contents of a ruptured infundibular cyst An “infundibular cyst” is an epidermal cyst because the infundibulum is a component of the epidermis. In contrast, an “isthmic-catagen cyst” is a follicular cy…

Differential Diagnosis in Dermatopathology

Infundibulo-folliculo-sebaceous cystic hamartoma vs. Steatocystoma

An inflammatory process that develops secondary to trauma, usually in the form of a penetrating injury or rupture of a follicle, and that proceeds through stages of granulation tissue with numerous extravasated erythrocytes, granulomatous inflammati…

Histologic Diagnosis of Inflammatory Skin Diseases

Images

…10.3.3B: Lymphocytes obscuring papillae of follicles early in catagen + 10.3.3C + 10.3.3D = Alopecia areata  The absence of a well defined bulb that encloses largely a papilla is evidence of catagen, all of the follicles pictured being i…

Differential Diagnosis in Dermatopathology

Discussions

…s a synonym for the entire outer sheath and the lining of the cyst under discussion here is like that of the upper part of that sheath only, namely, the isthmic portion. “Pilar” means hair and, therefore, “isthmic-catagen” cys…

Differential Diagnosis in Dermatopathology

Differential Diagnosis

Infundibulo-folliculo-sebaceous cystic hamartoma Steatocystoma 1. Situated mostly in the dermis as a rule; sometimes also the subcutaneous fat 1. Situated in either the dermis or the subcutaneous fat, or both together 2. Cyst does not “p…

Resolving Quandaries in Dermatology, Pathology & Dermatopathology

Anagen Effluvium?

…ich continue in their growing phase without being thrown into catagen.” Kligman AM. Pathologic dynamics of human hair loss, I: telogen effluvium. Arch Dermatol 1961;83:175–98. “Only a limited number of detailed case reports describing C…

Differential Diagnosis in Dermatopathology

Dilated pore vs. Pilar sheath acanthoma

An inflammatory process that develops secondary to trauma, usually in the form of a penetrating injury or rupture of a follicle, and that proceeds through stages of granulation tissue with numerous extravasated erythrocytes, granulomatous inflammati…