Adult rhabdomyoma in fine needle aspirates. A report of two cases.

BACKGROUND: Adult rhabdomyoma (ARh) is a rare, benign tumor arising most frequently in the head and neck region and sometimes mimicking malignant tumors clinically. Correct preoperative evaluation of this tumor is of crucial importance as its treatment is complete excision only and not radical surgery. CASES: Two patients with ARh, one tumor presenting near the submandibular gland and the other in the thyroid area, are reported. The first tumor was correctly diagnosed by fine needle aspiration cytology. The second, clinically suspected to be a colloid goiter, was preoperatively diagnosed as such cytologically as well. After the tumor was excised, reexamination of the cytologic specimen disclosed follicle cells admixed with single cells from ARh; these had been interpreted as colloid fragments at the time of primary evaluation. CONCLUSION: Fine needle aspiration evaluation of ARh may be problematic due to the rarity of the tumor and to the similarity of the tumor cells to normal striated muscle and to other tumors in which cells with abundant granular cytoplasm are characteristic. With an awareness of the cytologic features of this uncommon tumor, cytopathologists can render a correct diagnosis.