Primary parotid tuberculosis mimicking parotid neoplasm: a case report

<p>Abstract</p> <p>Introduction</p> <p>Tuberculosis of the parotid gland is a rare clinical entity which causes some difficulties in diagnosis because of the similarities in presentation to that of a neoplasm. Diagnosis mainly relies in the treating physician having a high index of suspicion. The diagnosis is generally overlooked by otolaryngologists and most cases are undergoing unnecessary surgery.</p> <p>Case presentation</p> <p>A 20-year-old male presented with a mass in the right parotid region. The mass had been present for one year. Physical examination revealed a mobile, non-tender mass occupying the superficial lobe of the right parotid gland. Radiologic investigations revealed a well-defined, solid, mass lesion located in the posterior part of the superficial lobe of the right parotid gland. A provisional diagnosis of a neoplasm of the parotid gland was made and a right superficial parotidectomy was performed. Histopathologic examination of the specimen was reported as tuberculosis of the parotid gland. The patient was commenced on antitubercular chemotherapy.</p> <p>Conclusion</p> <p>Although rare, tuberculosis should be kept in mind and considered in the differential diagnosis of patients presenting with a solitary tumor in the parotid gland in order to avoid unnecessary surgery.</p

Tetanus toxin Hc fragment induces the formation of ceramide platforms and protects neuronal cells against oxidative stress

Tetanus toxin (TeTx) is the protein, synthesized by the anaerobic bacteria Clostridium tetani, which causes tetanus disease. TeTx gains entry into target cells by means of its interaction with lipid rafts, which are membrane domains enriched in sphingomyelin and cholesterol. However, the exact mechanism of host membrane binding remains to be fully established. In the present study we used the recombinant carboxyl terminal fragment from TeTx (Hc-TeTx), the domain responsible for target neuron binding, showing that Hc-TeTx induces a moderate but rapid and sustained increase in the ceramide/sphingomyelin ratio in primary cultures of cerebellar granule neurons and in NGF-differentiated PC12 cells, as well as induces the formation of ceramide platforms in the plasma membrane. The mentioned increase is due to the promotion of neutral sphingomyelinase activity and not to the de novo synthesis, since GW4869, a specific neutral sphingomyelinase inhibitor, prevents neutral sphingomyelinase activity increase and formation of ceramide platforms. Moreover, neutral sphingomyelinase inhibition with GW4869 prevents Hc-TeTx-triggered signaling (Akt phosphorylation), as well as the protective effect of Hc-TeTx on PC12 cells subjected to oxidative stress, while siRNA directed against nSM2 prevents protection by Hc-TeTx of NSC-34 cells against oxidative insult. Finally, neutral sphingomyelinase activity seems not to be related with the internalization of Hc-TeTx into PC12 cells. Thus, the presented data shed light on the mechanisms triggered by TeTx after membrane binding, which could be related with the events leading to the neuroprotective action exerted by the Hc-TeTx fragment