The present study included four males and two females, with a mean age of 42.2±13.3 years (range: 27-67 years). The duration of symptoms ranged from 0.5 to 6 months, with a mean duration of 2.4±2.1 months. Common symptoms reported were headache (n=2), dizziness (n=2), gait difficulty (n=1), limb weakness (n=1), nausea (n=1), vomiting (n=1), impaired vision (n=1), and hearing loss (n=1). Radiologically, 33.3% of the patients had multifocal brain lesions, while other locations included the frontotemporal lobe, frontoparietal lobe, triangle area, and occipital lobe. Preoperative MRI scans were available for five patients, and a preoperative CT scan was available for one patient. The lesions appeared hypointense-isointense in one case and hypointense in four cases on plain T1WI. On plain T2WI, two cases showed isointense-hyperintense and three cases showed hypointensity. CT scans revealed high-density masses. Contrast enhancement was observed in all five available patients, and peritumoral edema was observed in all six patients. Gross total resection (GTR) was performed on three patients, while two patients underwent non-GTR, and one patient underwent biopsy. Unfortunately, case 3 was lost to follow-up. Three patients (60%) received postoperative radiotherapy and chemotherapy. After a mean follow-up of 25.3±27.9 months (range: 1-70 months), three patients died, resulting in a mean overall survival (OS) of 18.6±14.1 months (range: 10.2-34.8 months).
A total of 24 cases (11 males and 13 females) diagnosed with PIHSs were identified from previous papers published between 1996 and 2021. The mean age was 42.3±19.9 years (range: 1.4-69 years). Multifocal lesions were observed in 33.3% (8/24) of the patients. Peritumoral edema was observed in 81.25% (13/16) of the cases. Lesion morphology was categorized as solid in 77.8% (14/18) and cystic-solid in 22.2% (4/18) of the cases. Enhancement was observed in all 21 available cases. Nine patients (37.5%) achieved GTR. Postoperative radiotherapy and chemotherapy were administered to 11 patients (45.8%). After a mean follow-up of 10.9±11.5 months (range: 1-42 months), 14 patients (63.6%) died, resulting in a mean OS of 7.5±10.3 months (range: 1-42 months).
The mean follow-up period for the pooled cohort, which included five cases from our institute and 24 cases from the literature, was 13.5±16.6 months. The 0.5-year and 1-year overall survival (OS) rates were 65.6% and 39.1%, respectively. Univariate Cox regression analysis revealed that gross total resection (GTR) (p=0.005) and solitary lesions (p=0.010) were predictive of a better OS. However, factors such as age≤40 (p=0.976), male gender (p=0.382), radiotherapy (p=0.066), and chemotherapy (p=0.638) did not show a significant association with OS. Subsequently, GTR, solitary lesions, radiotherapy, and chemotherapy were included in the multivariate Cox regression analysis, which revealed that GTR was the only factor significantly predicting a better OS (p=0.027). The Kaplan-Meier analysis demonstrated that GTR (p=0.0013) and solitary lesions (p=0.0048) were associated with a better OS. The median survival time for patients with multifocal lesions was 4 months, whereas for patients with solitary lesions, it was 34.8 months.
Illustrative Case
Case 1
A 41-year-old male presented with symptoms of dizziness, gait difficulty, and hearing loss persisting for approximately three months. Neurological examination revealed ataxia of the left limb. An MRI scan revealed the presence of multifocal lesions in various areas of the brain, including the right CPA area, interventricular foramen area, right frontal lobe, and left temporal lobe. The lesion located in the right CPA area appeared as hypointense-isointense on T1WI, isointense-hyperintense on T2WI, and demonstrated homogeneous enhancement, indicating it as the primary mass responsible for the symptoms. Following multidisciplinary discussions, it was decided to perform the removal of the CPA lesion to alleviate the patient's symptoms. A right retrosigmoid approach was chosen for the surgery.
During the procedure, the tumor was visually observed to have a gray and white appearance with a well-developed blood supply. The tumor was found to originate from the lower cranial nerves and exhibited strong adherence to the brainstem and cerebellum, rendering gross total resection unattainable. Pathological examination of the tumor specimen revealed the presence of aggregates of histiocytoid cells characterized by abundant eosinophilic cytoplasm and marked nuclear pleomorphism. Immunohistochemistry analysis demonstrated positive staining for CD68, lysozyme, CD34, and vimentin, while negative staining was observed for CD3, CD20, CD1a, S-100, and CD79a. The Department of Neuropathology at Beijing Neurosurgical Institute confirmed the diagnosis of histiocytic sarcoma.
Following the surgery, the patient developed aspiration pneumonia, which was successfully treated with systemic antibiotic therapy. Unfortunately, the patient succumbed to tumor progression 10.7 months after the surgical intervention.