Auricular Embryonal Rhabdomyosarcoma With Parotid Gland and Cervical Infiltration in a Pediatric Patient With Congenital Ichthyosis Vulgaris: A Case Report.

Rhabdomyosarcoma (RMS), a rare pediatric soft tissue sarcoma, seldom involves the external ear. Congenital ichthyosis vulgaris (IV), a genetic disorder causing hyperkeratosis, has not been previously linked to RMS. We report the first case of embryonal RMS with unique extension in a patient with IV. A 13 year-old male with ichthyosis presented with a 1 year history of a progressive lesion in the right intertragic notch, unresponsive to antibiotics and topical therapies. Imaging revealed a mass infiltrating the parotid gland, external auditory canal, and sternocleidomastoid muscle. Wide surgical excision with facial nerve preservation was performed. Histopathology confirmed embryonal RMS. Postoperative chemoradiotherapy was initiated, and metastatic workup showed no dissemination. This case highlights diagnostic challenges in rare RMS locations, particularly when masked by dermatoses like ichthyosis. The association between ichthyosis and RMS remains speculative; potential mechanisms include ichthyosis. Clinicians should maintain a high index of suspicion for malignancy in persistent cutaneous lesions.