Cyril Fisher, MD, DSc, FRCPath

High magnification shows adult rhabdomyoma composed of large polygonal cells with copious eosinophilic cytoplasm (varying in staining intensity) and small round nuclei with uniform nucleoli.

Low magnification shows fetal rhabdomyoma of myxoid (immature) type. Slender spindle cells form loosely organized fascicles in myxoid stroma. Note the absence of pleomorphism and necrosis.



  • Benign tumor with skeletal muscle differentiation

  • Can arise in heart (cardiac rhabdomyoma) or extracardiac locations

  • Extracardiac tumors can be of adult or fetal histologic type


Developmental Anomaly

  • No associations for most extracardiac lesions

  • Cardiac rhabdomyoma can be associated with tuberous sclerosis

  • Some fetal rhabdomyomas associated with nevoid basal cell carcinoma syndrome

    • PTCH mutations

      • Inhibitory receptor in Sonic hedgehog signaling pathway



  • Incidence

    • Rare

  • Age

    • Adults; mean: 6th-7th decades

    • Fetal rhabdomyoma mostly in childhood; median: 4 years

      • About 1/2 in 1st year, or congenital

      • Rare examples in adults up to 6th decade

  • Gender

    • 75% in males

    • Genital rhabdomyoma mostly in middle-aged women

      • Rare cases in males


  • Rarely a cutaneous lesion

  • Most often in head and neck region, especially fetal rhabdomyoma

    • Larynx, oropharynx, mouth, neck

  • Genital lesions are subepithelial

    • Mostly in vagina, occasionally in vulva or cervix

  • Rare examples in males in paratesticular region or epididymis


  • Incidental finding

  • Painless mass

  • Difficulty breathing (laryngeal tumors)


  • Surgical approaches

    • Simple complete excision


  • Excellent after complete excision

  • Can recur if incompletely excised

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Jul 8, 2016 | Posted by in PATHOLOGY & LABORATORY MEDICINE | Comments Off on Rhabdomyoma
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