Atlas of Mohs and Frozen Section Cutaneous Pathology by Michael Morgan John R. Hamill & James M. Spencer

Author:Michael Morgan, John R. Hamill & James M. Spencer
Language: eng
Format: epub
Publisher: Springer New York, New York, NY

Abstract

The cutaneous adnexae broadly encompass appendageal structures of the skin including the follicle and associated sebaceous and apocrine glands as well as the eccrine sweat apparatus. Each of these structures can be subdivided on the basis of anatomic location, structure and function. Moreover, each of these subdivisions may give rise to benign or malignant neoplasms. These tumors will be discussed herein.

The adnexal neoplasms may be elementally thought of as caricatures of their derived anatomic structures imbued with phenotypic and genotypic attributes similar to their corresponding mature/developed adnexal counterpart. This chapter will deal with the most important eccrine and follicular benign adnexal neoplasms. Sebaceous and apocrine lesions will be accorded special consideration in Chapter 11.

The eccrine apparatus is found throughout the integument and consists of a complex series of coiled and straight glandular elements that originate in the deep dermis and subcutaneous fat coursing through the dermis as ducts to receive the epithelium as the acrosyringia. The glandular component comprises two cell types, one dark and the other light in appearance, that serve as a useful reminder of the important tumoral constituency of the deep dermal glandular-derived eccrine spiradenoma and cylindroma. The latter tumor often shows a close tumoral approximation whose disposition is likened to the appearance of a jigsaw puzzle. Such adnexal tumors may in turn derive from the ductular portion of the eccrine apparatus, giving rise to the hidradenoma/acrospiroma or the benign mixed tumor otherwise referred to as chondroid syringoma. Similarly, derivation from the upper dermal duct is the putative source of syringoma and as such is comprised of tadpole or tear-drop shaped glands with ducts. Finally, derivation from the acrosyringial duct is thought to be the source of poroma, producing a horizontally disposed neoplasm with uniform basaloid cells punctuated by eccrine ducts or pores. While each of these benign neoplasms may give rise to or be represented by their respective malignant counterparts, discussion of this topic will be forthcoming.

Likewise, the follicle is a complex multifunctional apparatus comprising the basilar germinative portion of the hair shaft that gives rise to the pilomatricoma, the middle isthmic portion bounded by the erector pilae muscle inferiorly and sebaceous duct superiorly, the source of tricholemmoma, and, finally, the normal keratinized upper portion termed the infundibulum. Pilomatricoma, faithful to its germinative origins, shows a basaloid highly proliferative component with hair-like abrupt keratinization and ghost cells. The most important benign simulants of basal cell carcinoma, known collectively as trichoblastoma or trichoepithelioma, principally derive from the isthmus and basilar portions of the follicle. As such, variable differentiation towards the lumen (ductular), outer root sheath, inner root sheath and the base (follicular germs) may be seen.

Poroma

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