A 43‐year‐old man with dural‐based mass with bone destruction

Clinical History

A 43‐year‐old gentleman was presented with swelling of his scalp for the past four months. Initially, it was a hard, painless swelling that gradually increased in size, but during the past month, it had become painful. The pain was described as dull, aching and intermittent, but was relieved by medication. There was no history of seizures, weakness, loss of consciousness, trauma, blurring of vision or vomiting. On examination, the vitals were stable with a Glasgow Coma Scale of E4V5M6. Bilateral pupils were of normal size with normal reaction. There were no sensory or motor deficits and cerebellar signs were negative. CT and MRI scans (with contrast) showed a destructive bone lesion over the parietal region (Figure 1A) in the midline with intact underlying dural structures and expanding the overlying galea (Figure 1B,C). With a preoperative diagnosis of midline frontoparietal calvarial tumor, a midline frontoparietal craniotomy was performed and near‐total excision was achieved. Intraoperatively, a firm‐to‐hard pinkish tumor was visualized in the calvarium which was adherent to the dura and infiltrating through the calvarial bone. The entire tumor with surrounding 1 cm of bony margin was excised. The postoperative period was uneventful.

Figure 1.

 

Microscopic Findings

Histology revealed a focally encapsulated hypercellular spindle cell tumor attached to the dura (Figure 1D) The tumor cells were arranged in interlacing short fascicles and sheets, with variable degrees of hyalinization and collagenization in the background (Figure 1E). The tumor cells were fusiform‐to‐oval in shape with vesicular chromatin, conspicuous nucleoli and moderate pink cytoplasm. The central core of the tumor showed necrosis. Mitotic activity was brisk (2‐3/HPF) in areas with cellular pleomorphism (Figure 1F). The tumor infiltrated the dura and overlying skull bone; however, no parenchymal invasion was identified. By immunohistochemistry, the tumor cells showed strong and diffuse positivity for vimentin, smooth muscle actin (SMA) (Figure 1G) and focally for desmin. The tumor cells were negative for Pan‐CK, EMA, Bcl‐2 and CD34. Electron microscopic examination revealed intermediate filaments of a width corresponding to those of actin filaments. What is your diagnosis?

Final Diagnosis

Primary intracranial leiomyosarcoma arising from the dura.

Primary intracranial leiomyosarcoma is extremely rare tumors with only 15 cases reported in the literature 1, 2, 3, 4. Most reported cases represent metastatic disease from other primary sites such as gastrointestinal tract, uterus and subcutaneous tissue 1; the primary tumors are postulated to arise from the mesenchymal cells of the dura matter or the cerebral blood vessels. All possible occult primary sites were excluded by whole‐body imaging including the positron electron transmission (PET) scan. The common diagnostic considerations for the dura‐based mass in a middle‐aged male include meningioma, hemangiopericytoma, primary melanocytic tumors, metastatic carcinoma/sarcoma and poorly recognized entity‐meningeal sarcoma. Morphology and panel of immunohistochemical stains aids in establishing the diagnosis. Besides the distinctive morphological features including plump spindle cells with abundant eosinophilic cytoplasm, immunoreactivity for muscle markers (SMA and desmin) confirmed the myoid nature of the neoplasm. Earlier reported cases suggest an association between AIDS, EBV and leiomyosarcoma 4; however, such an association was lacking in the present case. Specific serologic tests performed during the preoperative work‐up were negative and the immunohistochemistry performed for EBV nuclear antigen was negative.

Primary intracranial leiomyosarcoma, unlike glial tumors, has a metastatic risk outside the central nervous system. Metastatic disease has been reported in up to 40% of patients and is associated with a poor prognosis. Additionally, these are known to disseminate to neuraxis besides spread to lungs and bone hence, necessitating both neuraxis and whole‐body imaging (computed tomography and PET scan) along with lumbar cerebrospinal fluid cytology at diagnosis with regular follow‐up.

The prognosis and clinical behavior of primary intracranial leiomyosarcoma remains uncertain both due to disparities in the treatment offered and limited experience in treating such lesions owing to rarity. Nevertheless, the mainstay of treatment for all age groups appears to be the maximal safe surgical resection. The administration of chemotherapy and radiotherapy may improve the outcome.