# Case Report: The silent giant: biochemical-clinical dissociation in a large cystic pheochromocytoma

## TL;DR

A large, asymptomatic pheochromocytoma was found in a patient, highlighting the importance of biochemical testing over symptoms for proper treatment.

## Contribution

The case highlights biochemical-clinical dissociation in a large pheochromocytoma and emphasizes the need for mandatory preoperative alpha-blockade.

## Key findings

- The tumor showed markedly elevated normetanephrine levels despite no clinical symptoms.
- Histopathology confirmed a pheochromocytoma with SDHB expression loss.
- Successful management was achieved with preoperative alpha-blockade and laparoscopic surgery.

## Abstract

Asymptomatic pheochromocytomas are increasingly detected as incidentalomas. However, large tumors presenting with marked biochemical elevation but complete clinical silence (“biochemical-clinical dissociation”) are rare and prone to catastrophic mismanagement if mistaken for non-functional masses.

We report a case of a 43-year-old normotensive female presenting with a large (57×53 mm) incidental left adrenal mass. Abdominal imaging revealed a cystic-solid tumor with intratumoral hemorrhage. Despite the complete absence of sympathetic symptoms, biochemical evaluation showed markedly elevated plasma normetanephrine levels (1168.0 pg/ml), indicating significant secretory activity. The patient was successfully managed with preoperative alpha-blockade (doxazosin) and volume expansion, followed by an uneventful transperitoneal laparoscopic adrenalectomy. Histopathology confirmed a pheochromocytoma with loss of SDHB expression.

This suggests a multifactorial mechanism involving cystic sequestration and biochemical alterations associated with SDHB deficiency. Clinicians must recognize that biochemistry, not symptoms, dictates management. Mandatory preoperative α-blockade remains the cornerstone for preventing lethal intraoperative hemodynamic crises in these “silent” yet biochemically active tumors.