91
Adnexal Neoplasms
• Adnexal neoplasms are tumors, more commonly benign, that show features of cutaneous adnexal structures (Fig. 91.1), e.g. hair (Table 91.1), sebaceous glands (Table 91.2), apocrine glands and eccrine glands (Table 91.3).
Fig. 91.1 Folliculo-sebaceous-apocrine unit and eccrine sweat gland. Adnexal tumors showing differentiation toward the hair follicle, sebaceous gland, apocrine gland, and eccrine gland are listed in correspondingly colored boxes. Important entities are in capital letters; entities associated with syndromes are in italics (see Tables 91.1–91.3). *Can show germinal differentiation; **differentiation toward entire follicle.
Table 91.1
Benign and malignant tumors with follicular differentiation.
Cysts (e.g. epidermoid and pilar) are discussed in Chapter 90. BHD encodes folliculin, a tumor suppressor; CYLD encodes a deubiquinating enzyme; APC encodes a protein that regulates cell adhesion/migration.
* Patients generally have multiple tumors when associated with a syndrome.
† Rare tumors include pilomatrical carcinoma and trichilemmal carcinoma.
