Malignant proliferating trichilemmal tumor (MPTT) is a rare adnexal neoplasm originating from the outer root sheath of the hair follicle. It most often arises from a pre-existing proliferating trichilemmal (pilar) tumor. MPTT occurs most commonly (approximately 90%) on the scalp, although other anatomic locations have been reported. Women over the age of 40 are most often affected.
The diagnosis of MPTT is based mainly on histological features. A histological classification system has been proposed to differentiate the more common and benign proliferating trichilemmal tumor (PTT) from low-grade and high-grade MPTTs, which have potential for metastasis.
Recurrences are not uncommon. MPTT is at high risk for metastasis, with regional and distant metastatic disease in up to 25% of patients.
More than 40 cases of MPTT have been described in the literature, including 12 cases with metastatic disease and several mortalities.
Malignant proliferating trichilemmal tumor
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Synopsis
Codes
ICD10CM:
C44.49 – Other specified malignant neoplasm of skin of scalp and neck
SNOMEDCT:
399878004 – Malignant neoplasm with pilar differentiation
446023005 – Proliferating trichilemmal tumor
C44.49 – Other specified malignant neoplasm of skin of scalp and neck
SNOMEDCT:
399878004 – Malignant neoplasm with pilar differentiation
446023005 – Proliferating trichilemmal tumor
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Last Reviewed:02/14/2019
Last Updated:06/12/2019
Last Updated:06/12/2019
Malignant proliferating trichilemmal tumor