Lipid-Rich Variant of Pancreatic Endocrine Neoplasms

Definition

A lipid rich variant of pancreatic endocrine neoplasia (pancreatic islet cell tumour) showing foamy or microvesicular cytoplasm.

Epidemiology

Cases may be associated with Hippel-Lindau syndrome or with MEN-1¹.

Clinical features

Familial cases tend to occur in younger adults. These tumours are hormonally non-functional.

Macroscopic appearances

Most tumours are confined to the pancreas.

Histopathology

The growth pattern is usually diffuse but there may be prominent nesting. The microvesicular cytoplasm causes the tumours to resemble those of xanthoma cells and obscures the usual endocrine appearance. In particular, a salt-and-pepper chromatin pattern is lacking. The tumour vasculature is often sinusoidal.

Immunohistochemistry

	Chromogranin	11/111
	Synaptophysin	11/111
	MUC6	0/101
	Melan-A	0/101
	Hypoxia-inducible factor (HIF) -1a	1/101
	Inhibin	1/101

Ultrastructure

The cytoplasmic vesicles contain lipid. Neurosecretory granules are also present.

Differential diagnosis

Clear cell pancreatic neuroendocrine neoplasm are strongly associated with Hippel Lindau Syndrome

Solid pseudopapillary tumour of the pancreas

• Foamy-gland adenocarcinoma

• Low-grade mucinous adenocarcinoma

• Ductal adenocarcinoma with clear cell features

• Serous adenoma

  Metastatic adrenal cortical neoplasm: also shows a sinusoidal vasculature. They are positive for CD68.

• Metastatic renal clear cell carcinoma

• Metastatic steroid-secreting tumour of ovary

• metastatic clear cell hepatocellular carcinoma

References

¹ Singh R, Basturk O, Klimstra DS, et al. Lipid-rich variant of pancreatic endocrine neoplasms. Am J Surg Pathol 2006; 30:194-200

This page last revised 9.4.2006.

©SMUHT/PW Bishop