Subcutaneous metastasis in medulloblastoma: A case report and review of literature
This 9-year-old boy presented with a history of gait ataxia for 1 month, and headache, vomiting and progressive drowsiness for 20 days. Computed tomography (CT) scan and magnetic resonance imaging (MRI) brain showed the presence of a midline posterior fossa mass with small punctate calcification and heterogeneous enhancement, causing obstructive hydrocephalus. Due to his poor sensorium, the child underwent an urgent right ventriculo-peritoneal shunt. Following this, he underwent midline suboccipital craniectomy, C1 posterior arch excision and gross total decompression of tumor. Post-operative imaging showed complete excision of the tumor. He was referred to an Oncology Center, where he was treated with cranio-spinal irradiation, along with chemotherapy. At 1 year follow-up, patient was doing well apart from mild gait ataxia, and a cranio-spinal MRI did not show any evidence of residual disease. However, CT scan done 27 months after surgery, showed a 5 mm × 15 mm enhancing lesion on left cerebellar hemisphere extending through left foramen of Luschka. Patient was advised excision of the tumor, followed by further adjuvant therapy, however he was lost to follow-up after that. After 4 years of primary surgery, patient presented with a swelling in right masseter region. He also had occasional vomiting and gait ataxia. MRI brain and spine showed a 3.6 cm × 2.7 cm irregular lobulated heterogeneous lesion involving left middle cerebellar peduncle and inferior vermis with diffuse pachymeningeal thickening and enhancement and diffuse spinal metastasis. In addition, there was a well-defined solid cystic lesion, heterointense, with areas of T2 shortening, enhancing brilliantly on contrast, in right masseter region. The lesion was located superficial to the mandible and was infiltrating the muscle and coming to the subcutaneous plane []. Imaging character of the lesion was same as that of cerebellar lesion. Chest X-ray, Ultrasound of the abdomen and bone scan was performed to rule out any other ENM, and were all negative. There were no other ENM. Fine needle aspiration cytology from the subcutaneous swelling showed numerous large basophilic cells with high nuclear cytoplasmic ratio, suggestive of medulloblastoma []. In view of disseminated metastasis, the child was given palliative and supportive care. He died 11 month after the diagnosis of ENM because of disseminated disease.