Transketolase-like protein 1 expression in recurrent oral squamous cell carcinoma after curative resection: a case report

Background. Squamous cell carcinoma of the oral cavity (OSCC) is one of the common malignant tumors of the head and neck worldwide. Transketolase-like protein 1 (TKTL1), which has an important role in controlling the nonoxidative pentose-phosphate pathway, is significantly overexpressed in several different tumor entities. TKTL1 overexpression confers an advantage on malignant cells, allowing them to grow faster and to metastasize. However, to date, there is no link between TKTL1 expression and (metastatic) OSCC. Case Report. We report the first case of simultaneous penile, lung, bone, and suprarenal gland metastases from a primary bifocal moderately differentiated keratinized OSCC in a 53-year-old man that occurred 7 months after primary diagnosis. The tumor stained positive for TKTL1, epithelial growth factor receptor, and cyclooxygenase-2 (COX-2). To the best of our knowledge, no case has been reported to date on the manifestation of synchronous distant metastases of OSCC in the penile and the suprarenal gland. Conclusions. Secondary malignancy of the penis is an uncommon clinical entity. Because of the possibility of penile metastatic spread, this case report suggests that particular attention should be paid to physical examination of patients who undergo surgical procedures from OSCC, including those seemingly without metastatic disease. For the first time, our case provides evidence that TKTL1 expression in recurrent OSCC might be associated with tumor formation and metastasis. Antibodies, small molecules, COX-2 inhibitors, or a ketogenic diet might be promising for therapy of metastatic OSCC.