RESUMO
BACKGROUND: Adamantinoma is a rare primary bone neoplasm of low malignant potential that may recur or metastasize in a mall percentage of patients. The myriad histologic patterns may cause difficulty in distinguishing this tumor from other primary or metastatic neoplasms. The cytomorphologic findings of fine needle aspiration biopsy were reported previously in only a small number of cases. CASE: A 32-year-old man presented with a mass in the distal side of the left leg that was diagnosed as classic adamantinoma by open biopsy. Local recurrence and pulmonary metastases were confirmed by fine needle aspiration biopsy, which showed low grade, uniform cells with nuclear membrane grooves. The patient underwent a below-the-knee amputation and is receiving palliative treatment for progressive pulmonary spread. CONCLUSION: The diagnosis of adamantinoma requires knowledge of compatible clinical and radiologic studies as well as understanding of the variable histologic patterns that one may encounter. Fine needle aspiration biopsy is particularly useful in the diagnosis of recurrent and metastatic adamantinoma. This case report describes a distinctive cytomorphologic feature of nuclear grooves that may be a useful aid in distinguishing the tumor cells of adamantinoma from other cell types.