Advantages by using the intradermal microbubbles for sentinel lymph node detection in penile cancer.

Dear Editor, Penile cancer has a relatively low incidence of 0.6% among all types of neoplasms. These incidents can reach up to 10% in the developing countries. Resection of the primary cancer and early dissection of nodal metastases may improve survival. Nevertheless, inguinal lymphadenectomy may have a negative impact on patient's quality of life due to possible surgical site infection, lymphocyst formation or lymphoedema. Sentinel lymph node (SLN) detection by radiopharmaceuticals, was first applied in penile cancer and is defined as the identification of the first regional lymph node by the primary site of cancer. In the case of penile cancer, the retrieval of a positive node necessitates a complete inguinofemoral nodal dissection including also the deep femoral lymph nodes. The method for identifying SLN has been successfully used in various cancers like vulval, breast cancers and melanomas. The utilization of contrast-enhanced ultrasonography (CEUS) combined with the administration of a contrast medium is used as a routine test for imaging tissue vasculature. This test is using various dispersions with sulfur hexafluoride gas microbubbles (SonoVue, Bracco Imaging). The mean diameter of these microbubbles is 2.5μm, smaller than the red blood cells diameter. The test has been recently applied in UK by the Maidstone group for the detection of SLN, in patients with breast cancer. The sentinel lymph node mapping CEUS technique combined with sulfur hexafluoride gas microbubbles is quite simple to apply and reasonably cost effective. Additionally, both in the blue dye and the radioactive colloid technique, the administrated substance may surpass the SLN to the next regional lymph node group giving confusing results. Moreover, this radioactive test needs to have a specific nuclear medicine department. Furthermore, there is a probability of anaphylactic reactions in 0.9% when injecting the blue dye. Local skin necrosis or/and skin tattooing at the injection site of the blue dye can last up to a year. In contrast to the above, the CEUS technique does not have these side effects, has a shorter time of application (approximately 30min) and causes less discomfort to the patients. Comparative studies using both the radioactive, the blue dye and the CEUS technique are warranted especially in penile carcinoma.