Simultaneous Muir-Torre and Turcot's syndrome: A case report and review of the literature
A 58-year-old male was diagnosed with colon cancer in February 1999, stage T3 N1 M0, which was treated by right hemicolectomy followed by adjuvant chemotherapy with 5-fluorouracil and leucovorin. He had no further recurrence of this tumor. In 2004, the patient started noticing “cysts” on his skin, for which he presented to a dermatologist. Biopsies of the skin lesions were taken. This prompted genetic testing on the patient's colonic adenocarcinoma, which revealed a mutation in the MSH2 gene, rendering the patient with a diagnosis of MTS. The patient presented to neurosurgical attention in 2007 with complaints of unsteady gait along with episodes of transient paresthesias involving the left arm, torso, and leg. His immediate family history included a deceased sister with a history of an astrocytoma and deceased mother with colon cancer; genetic testing was not performed on either.\nThe patient exhibited no neurologic deficits. Magnetic resonance imaging (MRI) studies revealed the presence of a well-demarcated, right posterior parietal mass roughly 2.2 cm in diameter. The tumor appeared as an isointense signal on the T1-weighted image with enhancement after administration of gadolinium contrast [], and as a hyperintense signal on the T2-weighted image. Computed tomography (CT) of the chest, abdomen, and pelvis was negative for masses.\nGiven the patient's history and the need to determine whether the brain mass represented a metastatic lesion from his previous colon cancer or a primary brain tumor, the patient initially underwent an MRI-guided, frameless stereotactic biopsy of the enhancing margin of the brain lesion for histologic diagnosis. Pathology revealed scattered atypical glial cells with monosomy of chromosome 7 in some of the cells. A distinct classification was unable to be determined. Therefore, roughly 2 weeks following the biopsy, the patient underwent an image-guided, awake right parietal craniotomy for resection of the tumor. The surgery proceeded without complication and the patient was discharged to home with no new neurological deficits on postoperative day one. The pathological report from this specimen definitively proved the tumor to be a glioblastoma multiforme (World Health Organization [WHO] grade 4) with positive immunohistochemical staining for p53 and GFAP and a Ki-67 proliferative index of 25%. Immunostaining for the mismatch repair proteins MSH2, MLH1, and MSH6 revealed that the tumor lacked staining with MSH2 and MSH6 with intact staining for MLH1, suggestive of a germline mutation. Molecular analysis demonstrated a high level of microsatellite instability by detecting evidence of microsatellite instability in 5 of 10 genetic loci used as markers.