Pilomatrixoma and Pilomatrical Carcinoma



Pilomatrixoma and Pilomatrical Carcinoma


Senait W. Dyson, MD

David Cassarino, MD, PhD










Low magnification of a pilomatrixoma shows a nodularcystic dermal-based lesion with a thin, partial rim of peripheral basaloid cells image surrounding central collections of eosinophilic and shadow cells image.






Higher magnification shows the 2 cell types of PMX: Basaloid image and shadow cells image. In this case, transitional cells image with pyknotic nuclei (prior to becoming shadow cells) are also seen.


TERMINOLOGY


Abbreviations



  • Pilomatrixoma (PMX)


Synonyms



  • Pilomatrixoma



    • Pilomatricoma


    • Calcifying epithelioma of Malherbe


    • Trichomatricoma


  • Pilomatrical carcinoma



    • Matrical carcinoma


    • Malignant pilomatrixoma


    • Pilomatrix carcinoma


Definitions



  • Pilomatrixoma



    • Benign dermal &/or subcutaneous tumor


    • Derived from matrical portion of hair follicle


  • Pilomatrical carcinoma



    • Malignant counterpart of pilomatrixoma


ETIOLOGY/PATHOGENESIS


Differentiation



  • Derived from matrix of hair follicle


  • Mutation in the CTNNB1 gene seen in both pilomatrixoma and pilomatrical carcinomas



    • CTNNB1 gene encodes β-catenin


Genetics



  • Rare cases are associated with myotonic dystrophy and Rubinstein-Taybi syndrome



    • Usually multiple pilomatrixomas present


  • Cysts of Gardner syndrome can show pilomatricoma-like changes


CLINICAL ISSUES


Epidemiology



  • Incidence



    • Pilomatrixoma



      • Relatively common


    • Pilomatrical carcinoma



      • Very rare


  • Age



    • Pilomatrixoma



      • Young children (1st and 2nd decade)


      • Rare in adults


    • Pilomatrical carcinoma



      • Elderly


  • Gender



    • Pilomatrixoma



      • No gender predilection


    • Pilomatrical carcinoma



      • Male predominance (M:F = 5:1)


Site



  • Pilomatrixoma and pilomatrical carcinoma



    • Head and neck and upper limbs

Jul 8, 2016 | Posted by in PATHOLOGY & LABORATORY MEDICINE | Comments Off on Pilomatrixoma and Pilomatrical Carcinoma

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