Study Design: Interventional Clinical Trial, single-arm, open-label~Estimated Enrollment: Up to 19 participants with NF2-associated cutaneous or subcutaneous schwannomas~Aims: To demonstrate change in peripheral schwannoma size following direct injection into the tumor with doxycycline hyclate.~Nineteen neurofibromatosis type 2-associated peripheral cutaneous or subcutaneous schwannomas between 0.5 cm and 4 cm in greatest diameter will be diagnosed clinically, photographed for documentation of location, and injected with between 0.1 ml to 4 ml of 10mg/ml doxycycline hyclate (Fresenius Kabi, Canton, MA). A maximum of three tumors per patient will be injected. The dose administered will be calculated based on tumor size, not to exceed the estimated volume of the tumor or a maximum of 4 ml. The tumor volume will be estimated by electronic caliper measure of the greatest tumor diameter (D). (V=4/3piR3 where R is the radius (R=D/2) is measured in millimeters and the dose calculated by Vmm3/1000 = injection volume in milliliters). Repeat measures will be made at 6-months and 1-year follow up (+/- 1 month) and documented with electronic calipers and photography. Injection of 1% lidocaine may be given pre-doxycycline to reduce injection pain.~Outcome: The primary outcome will be longitudinal change in tumor maximal diameter measured at 6-months and 1-year compared to baseline defined by a change of 25%. Secondary endpoints include patient reports of paresthesia, pain, skin breakdown or discoloration. Exploratory endpoints will be the change in the sum of maximal diameters.
In this research study the investigators want to learn more about an alternate, local treatment for skin schwannomas. Specifically, local doxycycline intra-tumoral injection will be performed as a potential treatment for NF2-related skin schwannomas, ultimately reducing the risks and costs associated with standard surgical removal of such skin tumors if successful.