Low back pain with axillary mass in a perimenopausal woman: A case of schwannomatosis mimicking metastasis.

Schwannomatosis is a rare neurocutaneous syndrome characterized by the presence of multiple schwannomas along the peripheral nerves, distinctly excluding the vestibular nerves. It is recognized as the third principal form of neurofibromatosis, alongside neurofibromatosis types 1 and 2. In this report, we discuss the case of a 45-year-old woman who initially sought medical attention for low back pain and swelling in her left axilla. Her magnetic resonance imaging revealed multiple enhancing intradural extramedullary lesions, along with a mass in the right upper thoracic region and another in the left axilla, raising suspicions of metastasis. However, a comprehensive analysis that aligned imaging results with histopathological findings confirmed the diagnosis of schwannomatosis. This case highlights the importance of differentiating between various conditions that can cause multiple intradural extramedullary masses, such as nerve sheath tumors, meningiomas, and metastasis. The presence of multiple schwannomas suggests a diagnosis of either neurofibromatosis type 2 or schwannomatosis, making the distinction between these two conditions critical for appropriate management.