Primary calcified rhabdoid meningioma of the cranio-cervical junction: A case report and review of literature
A 37-year-old female, allergic to erythromycin and who had family history for heart disease, hypercholesterolemia, hypertension, and diabetes, presented to neurosurgery clinic with 5 years of progressive subjective right upper extremity numbness and weakness. She also had some right occipital pain and facial numbness. She denied bowel or bladder changes. Her physical exam showed that she had subjective decreased sensation to pinprick in the right V1 and V2 distributions that became more marked in the V3 distribution. She had full strength in her left upper and left lower extremity. She had right-sided weakness of grade 4+ in most of the muscle groups on MRC scale. She had diminished sensation to light touch in a glove distribution in her right upper extremity. Sensation to light touch was otherwise normal in her left upper extremity and bilateral lower extremities. She had diminished proprioceptive sense in her right upper extremity as well as her bilateral lower extremities, right side worse than left side. Reflexes were 2+ and symmetrical. She had negative Hoffman's and Babinski's signs, positive Romberg sign, and difficulty with tandem gait. Finger-to-nose testing demonstrated no dysmetria.\nWith and without contrast, head and cranio-cervical junction computed tomography demonstrated a calcified mass, measuring 4.3 × 2.5 cm in the axial cuts [], and its height was 3.5 cm in sagittal reconstruction []. The mass was occupying the posterolateral portion of the right compartment of the cranio-cervical junction, displacing the medulla oblongata and upper spinal cord anteriorly to the left side. CTA demonstrated that the anterior portion of the mass engulfing the right vertebral artery [], hence transcondylar approach was planned for surgery.\nAn elective resection of the tumor was done using the transcondylar approach. Drilling of the posterior half of the occipital condyle along with the lateral mass of atlas bone was done to get the anterior pole of the tumor and perform careful dissection of the vertebral artery without any traction on the artery or the lower cranial nerves. The transcondylar approach is one of the skull base approaches that respect the paramount principles of skull base surgery by removing the basal bone to shorten the distance, improve the angle of work, and avoid any traction on the neural or vascular tissues. Intraoperatively, the tumor was a rock-like mass with scanty soft tissue at its periphery; it was engulfing the vertebral artery, posterior inferior cerebellar artery, and rootlets of lower cranial nerves in its substance []. The tumor was dissected from all these structures, and microscopic total resection was achieved. Frozen section suggested the diagnosis of meningioma.\nGrossly the specimen consisted of small fragments, most of which were sufficiently bony requiring decalcification and a minority was soft tissue. The soft tissue consisted of plump epithelioid cells with round to oval nuclei with prominent, usually single nucleolus. The striking feature was the nuclei frequently pushed to one side by an eosinophilic inclusion. The growth pattern was of nests and vague large whorls, with the foci becoming sheet-like. Necrosis was not present and mitoses were infrequent (2 or less/10 hpf).\nThe bony fragments had large, semi-confluent lamellated mineralized nodules, which were larger and somewhat different from psammoma bodies. The appearance was more suggestive of the lobular areas of tumor that had become acellular and calcified. Nevertheless, in the small amounts of viable tumor that could be found nestled around and between these mineralized concretions, the cells again had the eosinophilic rhabdoid morphology described. A vimentin immunostain was strongly positive and highlighted the cytoplasmic inclusions []. An MIB-1 proliferation index was quantitated at 12.9% (32/247) []. Although the amount of viable tumor was small, it exhibited WHO atypical features of large vesicular nuclei with prominent nucleoli, and focally sheet-like areas, and a significantly elevated MIB-1 index. The predominant cellular morphology was unequivocally and predominantly “rhabdoid,” although the tumor did not have a high mitotic rate or other anaplastic features.\nThe patient recovered very well. She noticed subjective improvement of the facial numbness and right-sided weakness few days after surgery. Definite histopathologic diagnosis of RM was made, and she received adjuvant intensity-modulated radiotherapy (IMRT) to the resection cavity (5220 Gy in 30 fractions). Her follow-up images after 14 months of surgery showed no recurrence in the tumor bed []. And the patient is alive normal with no disease till the date of writing this article (2 years after surgery).