DEK::AFF2 fusion-associated middle ear non-keratinizing squamous cell carcinoma: A case report

Primary squamous cell carcinoma (SCC) of the middle ear is rare, with non-keratinizing basaloid types being exceptionally uncommon. Distinguishing these cancers, often caused by viral factors (e.g., human papillomavirus or Epstein-Barr virus), or specific genetic alterations (e.g., bromodomain-containing protein 4-nuclear protein in testis fusion gene or Ewing sarcoma breakpoint region 1 gene fused with FLI chromosomal rearrangement), from other cranial conditions, is difficult. The recently identified DEK::AFF2 non-keratinizing SCC (NKSCC) is a novel subtype, fitting the World Health Organization classification of head and neck neoplasms. Less than 30 cases have been reported, highlighting the need for further studies.

A 55-year-old female patient first exhibited signs of illness over 10 years ago with persistent discomfort in the left external auditory canal, accompanied by skin irritation and bleeding. One month prior to seeking professional help, she experienced hearing loss and a sensation of obstruction in the affected ear, intermittently accompanied by ringing sounds, but no dizziness. An unusual mass was detected in the left auditory canal, confirmed through biopsy as moderately differentiated epithelial squamous cancer cells. This led to her admission to our hospital, where the final diagnosis confirmed as "NKSCC linked to a positive DEK::AFF2 fusion". The patient underwent surgical excision, followed by three cycles of local radiation therapy. Yet, metastasis to the lumbar vertebrae occurred 19 months post-treatment, followed by neck lymph node swelling detected three months after a physical examination. The patient died nine months later despite surgical removal of the metastatic lesion.

DEK::AFF2 gene fusion-associated NKSCC of the middle ear carries a grim prognosis and presents an emerging challenge.