title: Combined small cell carcinoma of the sinonasal tract associated with syndrome of inappropriate secretion of antidiuretic hormone: A case report.
abstract: Combined small cell carcinoma (SmCC) and squamous cell carcinoma (SqCC) is a rare malignant neoplasm in the head and neck. This study presents the first reported case of combined SmCC and SqCC originating from the sinonasal tract accompanied by syndrome of inappropriate secretion of antidiuretic hormone (SIADH). An 80-year-old female presented with a four-week history of right nasal discharge, nasal obstruction and left neck swelling. Imaging studies revealed a tumorous lesion in the maxillary sinus encroaching upon the right nasal cavity and left cervical lymph node (LN) swelling. An incisional biopsy carried out from the right maxillary sinus and LNs resulted in a diagnosis of combined SmCC with SqCC, staged as T4aN2cM0. Clinical examination revealed a sustained increase of antidiuretic hormone, hyponatremia with urinary sodium increase, and serum hypo-osmosis, resulting in SIADH. Water restriction to <1,000 ml/day was effective in improving sodium and osmotic imbalance. Curative treatment for the tumor was not prescribed due to the poor condition of the patient. Palliative treatment was administered and the patient succumbed to cachexia five months after histological diagnosis. The presence of SIADH may have marked implications for the treatment and prognosis of this disease.
authors.affiliation: Department of Otolaryngology-Head and Neck Surgery, Gunma University Graduate School of Medicine, Maebashi, Gunma 371-8511, Japan.
authors.forename: Mikiko
authors.initials: M
authors.lastname: Kayakabe
authors.affiliation: Department of Otolaryngology-Head and Neck Surgery, Gunma University Graduate School of Medicine, Maebashi, Gunma 371-8511, Japan.
authors.forename: Katsumasa
authors.initials: K
authors.lastname: Takahashi
authors.affiliation: Department of Otolaryngology-Head and Neck Surgery, Gunma University Graduate School of Medicine, Maebashi, Gunma 371-8511, Japan.
authors.forename: Tomofumi
authors.initials: T
authors.lastname: Okamiya
authors.affiliation: Department of Diagnostic Pathology, Gunma University Graduate School of Medicine, Maebashi, Gunma 371-8511, Japan.
authors.forename: Atsuki
authors.initials: A
authors.lastname: Segawa
authors.affiliation: Department of Diagnostic Pathology, Gunma University Graduate School of Medicine, Maebashi, Gunma 371-8511, Japan.
authors.forename: Tetsunari
authors.initials: T
authors.lastname: Oyama
authors.affiliation: Department of Otolaryngology-Head and Neck Surgery, Gunma University Graduate School of Medicine, Maebashi, Gunma 371-8511, Japan.
authors.forename: Kazuaki
authors.initials: K
authors.lastname: Chikamatsu
keywords: neuroendocrine; sinonasal tract; small cell carcinoma; squamous cell carcinoma; syndrome of inappropriate secretion of antidiuretic hormone