Custom surgical management of invasive malignant tumors of the scalp.

BACKGROUND: There is no universal management protocol concerning invasive malignant tumors of the scalp with bone and dura mater invasion. The aims of this study were to report and discuss our experience in the management of these forms of tumors. METHODS: We retrospectively reviewed all consecutive patients of microsurgical scalp reconstruction performed after resection of invasive cutaneous malignancies of the scalp, calvarium, and dura mater from 2017 to 2019, at Pitié-Salpêtrière University Hospital (Paris, France). RESULTS: Five patients met inclusion criteria. There were three squamous cell carcinomas and two sarcomas. Mean age at surgery was 63.6 years. The sex ratio male/female was 4. Two received radiation prior to resection and two patients had a history of prior scalp tumor surgery. All the patients underwent craniectomy and the mean cranial defect size was 41 cm2. Cranioplasty was performed in one patient. Soft tissue coverage was provided by free tissue transfer of latissimus dorsi muscle in all patients. In four patients, split thickness skin graft was performed in a second surgical stage few weeks later. There were no intraoperative complications and no complications into the donor site for the tissue transfer or the skin graft. Two patients had flap necrosis that healed after a new free flap of latissimus dorsi. CONCLUSIONS: Wide resection with craniectomy and reconstruction with microvascular free tissue transfer provides safe and reliable treatment of recalcitrant invasive scalp skin cancers. The surgical management of these complex patients is a challenge that must be conducted by trained, experienced, and multidisciplinary teams.

In vivo generation of hybrids between different species of RNA phages.

Hybrids between different species or genera of the single-stranded RNA coliphages have not been found in nature. Here, it has been shown that viable hybrids between different phage species can easily be generated in the laboratory by in vivo recombination. cDNA of species I phage MS2 located on a plasmid and lacking part of its 5' untranslated leader (5' UTR) was complemented with another plasmid carrying the 5' half of the genome of fr, a species I phage, or of KU1, a species II representative with low sequence similarity. When the two plasmids were present in the same cell there was spontaneous production of hybrid phages. Interestingly, these hybrids did not arise by a double or single crossover that would replace the missing MS2 sequences with those of fr or KU1. Rather, hybrids arose by attaching the complete 5' UTR of fr or KU1 to the 5' terminus of the defective MS2 phage. Several elements of the 5' UTR then occurred twice, one from KU1 (or fr) and the other from MS2. These redundant elements are in most cases deleted upon evolution of the hybrids. As a result, the 5' UTR of KU1 (or fr) then replaced that of MS2. It was earlier shown that this 5' UTR could assume two alternating structures that facilitated transient translation of the proximal maturation gene. Apparently, this timer function of the 5' UTR was exchangeable and could function independently of the rest of the genome. When hybrids were competed against wild-type, they were quickly outgrown, probably explaining their absence from natural isolates.