Intramuscular myxoma: sonographic appearance and sonographically guided needle biopsy.

The sonographic appearances of four intramuscular myxomas were reviewed. These tumors appeared as well-defined, ovoid masses surrounded by normal muscle. The echogenicity was decreased in all cases, and the presence of small fluid-filled clefts and cystic areas was noted in three of the four lesions. Color Doppler examination was performed in two cases and was negative. Sonographically guided fine-needle aspiration biopsy yielded a thick myxoid substance. Large-core cutting needle biopsy allowed establishment of the diagnosis in one of the two cases in which it was performed. The differential diagnosis of a well-demarcated intramuscular mass with multiple fluid-filled clefts or cystic areas should include intramuscular myxoma.