Head and neck intramuscular haemangioma: report of two cases with unusual localization.

Head and neck intramuscular haemangioma (IMH) is a benign, uncommon neoplasm arising most frequently in the masseter and trapezius muscles. It usually appears as an enlarging mass without specific clinical features and is therefore frequently misdiagnosed. We report two cases of IMH at unusual localizations: one involving the pterygoid muscles in a 30-year-old female and another one originating from the thyrohyoid muscles in a 38-year-old male. Preoperative evaluation included routine ENT examination, ultrasound (US) and CT scan. The preoperative clinical diagnoses were lymphangioma of the parapharyngeal space in the first case and atypical thyroid duct cyst in the second. Both patients were treated with open-neck approaches. The histopathologic diagnosis was capillary-type IMH in the first patient and cavernous-type IMH in the second. Postoperative courses were uneventful, and the patients were discharged within a few days. Clinical and US follow-ups were negative at 50 and 20 months, respectively. Preoperative diagnosis of head and neck IMH is rendered difficult by its rarity and non-specific clinical findings. Ample surgical excision is required for an adequate cure due to the frequent microscopically infiltrative pattern of diffusion of such a tumor into skeletal muscles, and long-term follow-up is mandatory to promptly treat any recurrence.