Postauricular fetal rhabdomyoma: Light and electron microscopic study

• Published in: Human pathology Vol. 13; no. 7; pp. 673 - 677
• Main Authors: Simha, Mangala, Doctor, Vatsala, Dalal, Subash, Manghani, Daya K., Dastur, Darab K.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.07.1982
• Subjects: Ear Neoplasms - pathology; Ear, External; Female; Humans; Infant; Microscopy, Electron; Rhabdomyoma - pathology
• ISSN: 0046-8177; 1532-8392
• DOI: 10.1016/S0046-8177(82)80014-2

This paper reports an unusual postauricular tumor in a female infant 40 days old, this being possibly the 11th case reported in the literature worldwide. Light microscopy of both paraffin and semithin sections showed strap-shaped bipolar cells intermingled with oval or circular cells with central nuclei. Some of the strap-shaped cells showed cross-striations in paraffin sections stained with phosphotungstic acid and in semi-thin araldite sections stained with toluidine blue. The latter also showed developing myotubules with growth cones. The tumor had a rich matrix of intercellular reticulin. Fine structural examination of the thin sections showed two types of developing striated muscle fibers: 1) circular or ovoid cells with small or large clumps of myofilaments and 2) somewhat larger, elongated cells containing more or less organized myofibrils, with formation of A and I bands and a basement membrane. These two represented, respectively, the least and the most developed stages of embryonal muscle fibers in this growth, which is probably a hamartoma rather than a true neoplasm.