52
Other Genodermatoses
This chapter discusses genetic skin diseases that are not covered in other chapters, including conditions featuring extracutaneous tumorigenesis, enzyme deficiencies, premature aging, and ectodermal dysplasia.
Disorders Featuring Extracutaneous Tumorigenesis
Cowden Disease and Other Forms of PTEN Hamartoma Tumor Syndrome
• Spectrum of autosomal dominant multisystem disorders that feature characteristic skin findings (Fig. 52.1), macrocephaly, hamartomatous overgrowth of a variety of tissues, and a predisposition to certain cancers (Table 52.1).
Fig. 52.1 Cowden disease. A Multiple skin-colored papules on the face, especially the nose, some of which are verrucous. B Multiple palmar keratoses, many with a glassy appearance or depression centrally. A, Courtesy, Kalman Watsky, MD; B, Courtesy, Joyce Rico, MD.
Table 52.1
Major clinical manifestations of PTEN hamartoma tumor syndrome.
This categorization reflects general tendencies, as the age of onset or recognition of these findings can vary. Criteria for PTEN gene testing and guidelines for surveillance in patients suspected to have Cowden disease are available at http://www.nccn.org/professionals/physician_gls/PDF/genetics_screening.pdf.
* Typically with fast-flow channels, intramuscular involvement, and ectopic fat; may have capillary, venous, and/or lymphatic components and associated soft tissue/bony overgrowth.
† Hamartomatous dysplastic gangliocytoma of the cerebellum.
BRR, Bannayan–Riley–Ruvalcaba syndrome.
Multiple Endocrine Neoplasia Syndromes
Muir–Torre Syndrome (MTS)
• Subtype of hereditary nonpolyposis colorectal cancer (Lynch) syndrome characterized by sebaceous neoplasms (e.g. sebaceous adenoma, sebaceoma, sebaceous carcinoma; Fig. 52.3, see Table 91.2) and keratoacanthomas (± sebaceous differentiation) as well as internal malignancies (Table 52.3).
Table 52.3
Factors associated with a greater likelihood of Muir–Torre syndrome (MTS).
* Testing can be performed on paraffin-embedded tissue; diagnostic yield may be higher for colonic lesions.
** For example, other GI cancers (small bowel, gastric, biliary, pancreatic), genitourinary cancers (endometrial, bladder, ureteral, renal), and glioblastoma.
† Sensitivity and specificity have varied and the overall utility is debated.
IHC, immunohistochemical; HNPCC, hereditary nonpolyposis colorectal cancer.
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