PMC

Ackerman AB. A Philosophy of Practice of surgical Pathology: Dermatopathology as Model. New York: Ardor Scribendi, Ltd., 1999. 470 pp with index. ISBN-10: 1893357023. ISBN-13: 978-1893357020.

A central infundibulocystic structure (red arrow) from which emanate smaller infundibula, from which, in turn, radiate numerous abnormal vellus follicles (blue arrow) that are surrounded by a characteristic stroma that resembles perifollicular sheath (green arrow). (Adapted with permission from Ackerman A, Reddy V, Soyer H. Trichoblastoma. In: Ackerman A, Reddy V, Soyer H, editors. Neoplasms with Follicular Differentiation. New York: Ardor Scribendi; 2001. p. 151. Copyright Ardor Scribendi. All rights reserved)

The large nodules are crowded and mostly solid (red arrow), but some are punctuated by an infundibulocystic structure that contains corneocytes (blue arrow). Follicular germlike structures are wedded often to a follicular papilla. Some neoplastic cells are necrotic, as evidence by pyknosis and karyorrhexis (green arrow). (Adapted with permission from Ackerman A, Reddy V, Soyer H. Trichoblastoma. In: Ackerman A, Reddy V, Soyer H, editors. Neoplasms with Follicular Differentiation. New York: Ardor Scribendi; 2001. p. 415. Copyright Ardor Scribendi. All rights reserved)

Warts with tricholemmal differentiation (cells of hyperplastic infundibula, not neoplasia of tricholemmal cells – i.e., cells of the outer sheath) in bulbous infundibula are known conventionally as tricholemmomas, but, in reality, they are not neoplasms, but hyperplasias of infundibular epithelium (red arrow) induced by papillomavirus. (Adapted with permission from Ackerman A, Reddy V, Soyer H. Trichoblastoma. In: Ackerman A, Reddy V, Soyer H, editors. Neoplasms with Follicular Differentiation. New York: Ardor Scribendi; 2001. p. 273. Copyright Ardor Scribendi. All rights reserved)