Adrenal incidentaloma: review of 197 patients and report of a drug-related false-positive urinary normetanephrine result.
OBJECTIVE
To determine the incidence and importance of functioning tumors among incidentally discovered adrenal masses in the era of laparoscopic surgery.


METHODS
We defined adrenal incidentaloma as a tumor detected during abdominal imaging for adrenal-unrelated reasons, and we reviewed 197 consecutive patients with adrenal incidentaloma diagnosed since we started laparoscopic adrenalectomy.


RESULTS
Incidentaloma was discovered initially in 91 (46%) patients and pheochromocytoma was detected as an incidentaloma in 21 (39%) of 54 patients. One patient, a 21-year-old woman taking mesalamine for ulcerative colitis, had a remarkably elevated urinary normetanephrine level, which resulted in the initial misdiagnosis of a 10-cm right adrenal incidentaloma as a pheochromocytoma. Laparoscopic right adrenalectomy resulted in a pathological diagnosis of ganglioneuroma. A series of urinary normetanephrine measurements were taken in parallel with the mesalamine doses. We found that other patients medicated with mesalamine, without adrenal tumors, had elevated urinary normetanephrine levels, confirming that mesalamine metabolites interfere with urinary normetanephrine measurements.


CONCLUSIONS
It is essential to diagnose the functional potential of adrenal incidentaloma preoperatively, and not to perform laparoscopic adrenalectomy for adrenal incidentaloma without careful evaluation first.
Ito
Takahiro
T
Department of Breast and Endocrine Surgery, Nagoya University School of Medicine, 65 Tsurumai-cho, Showa-ku, Nagoya, 466-8550, Japan.
Imai
Tsuneo
T
Kikumori
Toyone
T
Shibata
Arihiro
A
Horiba
Takao
T
Kobayashi
Hironobu
H
Sawaki
Masataka
M
Watanabe
Reiko
R
Nakao
Akimasa
A
Kiuchi
Tetsuya
T
D000310:Adrenal Gland Neoplasms / Q000175:diagnosis* / Q000601:surgery / Q000652:urine*; D000315:Adrenalectomy / Q000379:methods; D000328:Adult; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000493:pharmacokinetics / Q000627:therapeutic use; D014408:Biomarkers, Tumor / Q000652:urine*; D003093:Colitis, Ulcerative / Q000188:drug therapy / Q000652:urine; D003937:Diagnosis, Differential; D005189:False Positive Reactions; D005260:Female; D006801:Humans; D015994:Incidence; D010535:Laparoscopy; D008297:Male; D019804:Mesalamine / Q000493:pharmacokinetics* / Q000627:therapeutic use; D009647:Normetanephrine / Q000652:urine*; D010673:Pheochromocytoma / Q000175:diagnosis* / Q000601:surgery / Q000652:urine*; D014057:Tomography, X-Ray Computed; D016896:Treatment Outcome
D000894:Anti-Inflammatory Agents, Non-Steroidal; D014408:Biomarkers, Tumor; D009647:Normetanephrine; D019804:Mesalamine