Cellular Neurothekeoma



Cellular Neurothekeoma


Cyril Fisher, MD, DSc, FRCPath









Hematoxylin & eosin of a transverse section of whole tumor shows the smooth, dome-shaped outline. The lesion is confined to the dermis. The epidermis is thinned except at the lateral margins.






Hematoxylin & eosin shows rounded nests of cells separated by thin fibrous septa with some lymphocytes. The cells have uniform nuclei, a moderate amount of cytoplasm, and variably distinct cell margins.


TERMINOLOGY


Definitions



  • Multinodular dermal tumor composed of nests of rounded cells separated by delicate fibrous septa


  • Differs from dermal nerve sheath myxoma (a.k.a. neurothekeoma)


  • Cell type unknown; considered fibrohistiocytic


CLINICAL ISSUES


Epidemiology



  • Incidence



    • Rare


  • Age



    • Young adults, most 15-25 years


  • Gender



    • M = F


  • Ethnicity



    • No predilection


Site



  • Head and neck and upper extremity most common


Presentation



  • Slow growing



    • Elevated dermal nodule


    • Painless


Treatment



  • Surgical approaches



    • Simple excision


Prognosis



  • Reported cases have behaved in benign fashion


  • Occasional recurrence, especially if incompletely excised


  • Atypical histologic features have no prognostic significance


MACROSCOPIC FEATURES


General Features



  • Rounded or dome-shaped skin lesion


  • Pale or tan


Size



  • ≤ 2 cm diameter


MICROSCOPIC PATHOLOGY


Histologic Features



  • ˜ 50% confined to dermis; 48% involve superficial subcutis


  • Nests of rounded cells



    • Uniform nuclei, scanty cytoplasm


    • Occasional spindling of cells, especially in myxoid areas


  • Nests separated by thin fibrous septa


  • Myxoid change in 20%



    • 30% are mixed cellular and myxoid lesions


  • Nuclear atypia in 25%


  • Mitoses occasionally seen up to 3 per 10 HPF


  • Multinucleated cells in 40%


  • Osteoclast-like cells in 30%


  • Occasional plexiform pattern


Predominant Pattern/Injury Type



  • Nested


Predominant Cell/Compartment Type



  • Mesenchymal, fibrohistiocytic

Jul 9, 2016 | Posted by in PATHOLOGY & LABORATORY MEDICINE | Comments Off on Cellular Neurothekeoma
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