Applied Radiology

Diagnosis

Thoracic ganglioneuroma presenting with the watery diarrhea, hypokalemia, and achlorhydria (WDHA) syndrome.

Findings

Findings indicative of a posterior mediastinal mass on plain film and chest computed tomography (CT) scans suggest the diagnosis of a neurogenic tumor, as 95% of pediatric posterior mediastinal masses are of neurogenic origin. The primary differential considerations are tumors of sympathetic ganglion origin (i.e., neuroblastoma, ganglioneuroblastoma, and ganglioneuroma).¹ The patient's age favored a neuroblastoma or ganglioneuroblastoma, as ganglioneuroma tends to occur in older children. Plain film findings of thoracic neuroblastoma include a posterior mediastinal mass, possibly associated with ribs that are splayed or eroded or both; calcifications; and enlarged intervertebral foramina in cases with intraspinal extension of tumor. CT demonstrates calcification in approximately 90% of neuroblastomas. Magnetic resonance (MR) imaging is the test of choice for thorough evaluation of intraspinal extension of tumor.²

Discussion

The WDHA syndrome is an unusual paraneoplastic condition caused by excess vasoactive intestinal peptide (VIP) secretion by certain tumors, including the neuroblastoma-ganglioneuroblastoma-ganglioneuroma spectrum in children and non-beta pancreatic islet cell tumors, squamous cell tumors of the lung or esophagus, cutaneous mast cell tumors, and pheochromocytomas in adults.³ Ganglioneuromatosis of the small intestine and pancreas, causing hypersecretion of VIP, has been reported.⁴ The WDHA syndrome has also been referred to as the vipoma syndrome, pancreatic cholera, the watery diarrhea syndrome, and the Verner-Morrison syndrome after its discoverers in 1958.⁵ Clinically, the onset of WDHA syndrome is typically insidious and diagnosis is often delayed for months or even years. The clinical hallmark is an unremitting secretory diarrhea that persists despite fasting. Diagnosis requires documentation of elevated serum VIP levels with subsequent localization of the VIP-secreting tumor. Surgical resection is usually curative, as it was in this case.

1. Hedlund GL, Griscom NT, Cleveland RH, Kirks DR: Respiratory system. In: Kirks DR (ed): Practical Pediatric Imaging: Diagnostic Radiology of Infants and Children, ed 3, pp 790-792. Philadelphia, Lippincott-Raven, 1998.
2. Abramson SJ:Adrenal neoplasms in children. Radiol Clin North Am 35:1415-1453, 1997.
3. Grier JF:WDHA (watery diarrhea, hypokalemia, achlorhydria) syndrome: Clinical features, diagnosis, and treatment. South Med J 88:22-24, 1995.
4. Shulman DI, McClenathan DT, Harmel RP, et al: Ganglioneuromatosis involving the small intestine and pancreas of a child and causing hypersecretion of vasoactive intestinal polypeptide. J Pediatr Gastroenterol Nutri 22:212-218, 1996.
5. Castleberry RP:Biology and treatment of neuroblastoma. Pediatr Clin North Am 44:919936, 1997.