Unknown primary cancer presenting as an adrenal mass: Frequency and implications for diagnostic evaluation of adrenal incidentalomas

Background. Fine-needle aspiration biopsy to identify adrenal metastasis fr om an occult primary malignancy has been recommended as part of the evaluat ion of the patient who presents with an incidentally discovered adrenal mas s. This recommendation was assessed by examining the frequency of adrenal i nvolvement in patients with suspected unknown primary cancer. Methods. Data from 1715 patients referred for evaluation of suspected unkno wn primary cancer were retrospectively reviewed. Results, Of 1639 patients found to have cancer the adrenal gland was identi fied as a site of involvement at presentation in 95 (5.8%). Involvement was limited to the adrenal gland in 4 patients (0.2%). All 4 patients had larg e (greater than or equal to 6 cm) adrenal tumors, 3 of 4 had bilateral invo lvement, and all had symptoms that otherwise mandated evaluation for an occ ult malignancy; none had a true adrenal incidentaloma. Conclusions, Although cancer of an unknown primary site occasionally involv es the adrenal gland, metastatic cancer presenting as a true adrenal incide ntaloma is extremely rare. Therefore, in the absence of a history of prior malignancy or symptoms, physical examination findings, radiographic finding s, or laboratory findings suggestive of an occult malignancy, we do not rec ommend fine-needle aspiration biopsy as part of the diagnostic evaluation o f the patient who presents with a unilateral adrenal mass.