Crinophagy in neuroblastoma: a case report and review of the literature.

Crinophagy is a well-described ultraphysiological phenomenon encountered in a variety of cells and tissues. This process reflects a form of autophagy in which degradation of excess or nonfunctional cellular constituents occurs, specifically of neuroendocrine granules. The diagnostic ultrastructural features are the identification of neuroendocrine granules within lysosomes, often encased in or accompanied by myelin bodies. An impressive variety of neuroendocrine/secretory cells and tumors have demonstrated crinophagy from the neuroendocrine cells of the pancreas, small bowel, prostate, and urinary tract. To our knowledge, however, crinophagy has not been previously described in neuroblastoma, despite the fact that these tumors characteristically produce neuroendocrine granules in abundance. This case further supports the idea that crinophagy represents a common ultrastructural mechanism for the disposal and degradation of excess neuroendocrine granules.