Left Atrial Myxoma Infected With Fusobacterium Nucleatum.

Cardiac myxomas are the most common primary cardiac tumours in adults. Clinical presentation is variable, with few cases of infected myxomas reported in the literature. We describe a rare case of a 63-year-old patient who presented with splenic abscesses and a left atrial mass suggestive of emboligen myxoma. The patient underwent a successful emergency sur- gical excision of the atrial mass followed by splenectomy. Blood cultures were positive for Fusobacterium nucleatum, whereas the histopathological examination of the excised mass confirmed the presence of a myxoma with a marked inflammatory infiltrate. All these findings allowed us to confirm the diagnosis of definite infected myxoma. Some aspects related to the aetiology, diagnosis and management of this entity are discussed.

Merkel cells of human oral mucosa express the pluripotent stem cell transcription factor Sox2.

Merkel cells are neuroendocrine cells associated to a neural sensitive ending and localized primarily in the epidermis, although they are also found in oral mucosa. Sox2 or SRY-box2 is a key transcription factor important in the maintenance of embryonic neural crest stem cell pluripotency. Sox2 has been described in Merkel cells of skin and in Merkel cell carcinomas, but not specifically in oral Merkel cells. The aims of the present study were to analyze the density of Merkel cells in human oral mucosa and to study the expression of Sox2 in these cells. For these purposes, immunohistochemical analyses for Sox2 and CK20 (the best marker for Merkel cells) were automatically performed on sections of normal human oral mucosa. Double immunofluorescence for Sox2 and CK20 was also performed. To analyze the density of Merkel cells, CK20 positive cells were counted in each sample and the length of the epithelial apical edge was measured (cells/mm). Merkel cells, demonstrated by CK20 immunoreactivity, were found in 95% of oral mucosa specimens studied (n=21). Mean density of Merkel cells in oral mucosa was 1.71±2.34 cells/mm. Sox2 immunoreactivity was found in the nuclei of scattered cells located at the basal layer. Serial sections immunostained for Sox2 and CK20 showed that Sox2-positive cells of oral mucosa coexpressed CK20, confirming that they were Merkel cells. Immunofluorescence for Sox2 and CK20 showed colocalization of both markers, demonstrating that virtually all oral Merkel cells expressed Sox2. This transcription factor could play a role in Merkel cell maturation and maintenance.