Abraham, Susan C.

Abstract Esophageal lichen planus is an underrecognized condition, with fewer than 50 cases reported to date. Unlike cutaneous lichen planus, esophageal lichen planus occurs almost exclusively in middle-aged or older women who also have oral involvement. It commonly involves the proximal esophagus and manifests as progressive dysphagia and odynophagia. Endoscopic findings can include lacy white papules, pinpoint erosions, desquamation, pseudomembranes, and stenosis. Histologic features of esophageal lichen planus have only rarely been illustrated. They differ from those of cutaneous disease in several respects, including the presence of parakeratosis, epithelial atrophy, and lack of hypergranulosis. Correct diagnosis of esophageal lichen planus is difficult but bears important therapeutic implications. It is typically a chronic and relapsing condition that can require systemic or local immunosuppressive therapy and repeated endoscopic dilatations for esophageal strictures. Esophageal lichen planus may have malignant potential, as evidenced by 3 patients who developed squamous carcinoma of the esophagus after longstanding disease.

Abstract Giant fibrovascular polyp of the esophagus is a rare but dramatic entity. These large polyps arise in the proximal esophagus and can cause airway obstruction secondary to mechanical pressure on the larynx, or they can present as a mass that is regurgitated into the oral cavity. We present a 66-year-old man who complained of nausea and vomiting that were associated with a fibrovascular polyp protruding into the mouth. He had also experienced several episodes of syncope resulting from intermittent airway obstruction. He underwent an open resection of an 11.8-cm fibrovascular polyp and an endoscopic resection of a second fibrovascular polyp 2 days later. Histopathologically, both masses were composed of a mixture of mature adipose tissue lobules and fibrovascular tissue, lined by reactive squamous epithelium. Despite their large size, giant fibrovascular polyps should be recognized radiologically and pathologically as benign lesions. However, they can result in significant morbidity.

The physiological role of the mitotic checkpoint protein Bub1 is unknown. To study this role, we generated a series of mutant mice with a gradient of reduced Bub1 expression using wild-type, hypomorphic, and knockout alleles. Bub1 hypomorphic mice are viable, fertile, and overtly normal despite weakened mitotic checkpoint activity and high percentages of aneuploid cells. Bub1 haploinsufficient mice, which have a milder reduction in Bub1 protein than Bub1 hypomorphic mice, also exhibit reduced checkpoint activity and increased aneuploidy, but to a lesser extent. Although cells from Bub1 hypomorphic and haploinsufficient mice have similar rates of chromosome missegregation, cell death after an aberrant separation decreases dramatically with declining Bub1 levels. Importantly, Bub1 hypomorphic mice are highly susceptible to spontaneous tumors, whereas Bub1 haploinsufficient mice are not. These findings demonstrate that loss of Bub1 below a critical threshold drives spontaneous tumorigenesis and suggest that in addition to ensuring proper chromosome segregation, Bub1 is important for mediating cell death when chromosomes missegregate.