Acute (gangrenous) esophageal necrosis (black esophagus). A rare form of injury with specific histologic features and diverse clinical associations with a common pathogenesis.

Acute esophageal necrosis (AEN) also known as black esophagus is a rare form of injury to the esophageal mucosa that complicates a variety of clinical conditions. It is characterized by circumferential black discoloration of the mucosa. There is little information relating to the histopathologic features and pathogenesis of this condition. In this study we describe the histopathologic features of six cases of AEN (3 autopsy and 3 biopsy cases) and compared the finding to 26 cases of ulcerated esophagitis. Cases and controls were assessed for type of necrosis, inflammatory cells, vascular thrombi, pigment deposits, granulation tissue and presence of viable mucosa. Cases were evaluated with histochemical stains for iron and microorganisms and immunohistochemical stains to inflammatory cells (myeloperoxidase, CD20, CD3 and CD163), squamous cells (pancytokeratin and p40) and muscle (smooth muscle actin). Most patients were males (60%) with an average age of 58 years. All specimens show the characteristic black discoloration of the mucosa. Microscopic examination revealed a distinct band of basophilic necrosis, Prussian blue-negative pigment deposits and fibrin thrombi in vessels. Myeloperoxidase-positive neutrophils were seen beneath the area of necrosis and CD163-positive macrophages throughout the esophagus. Basophilic necrosis was never seen in control cases. Only one control case showed intravascular thrombi and pigment deposits. We conclude that the combination of basophilic necrosis, intravascular thrombi and pigment deposits are diagnostic of AEN. We theorize that microvascular occlusion is the unifying lesion that explains the diversity of conditions associated with this disorder.