What Tactics Should a Surgeon Choose to Treat a Black Extracerebral Tumor? A Case Report of Psammomatous Melanotic Schwannoma of the Meckel Cave and Literature Review

Flatness of the Meckel cave may cause primary trigeminal neuralgia: a radiomics-based study

Background

Neurovascular contact (NVC) is the main cause of primary trigeminal neuralgia (PTN); however, cases of PTN without NVC are still observed. In this study, the Meckel cave (MC) morphology in PTN were analyzed by radiomics and compared to healthy controls (HCs) to explore the cause of PTN.

Methods

We studied the 3.0T MRI data of 115 patients with PTN and 46 HCs. Bilateral MC was modeled using the 3D Slicer software, and the morphological characteristics of MC were analyzed using the radiomics method.

Results

The right side incidence rate in the PTN group was higher than the left side incidence. By analyzing the flatness feature of MC, we observed that the affected side of the PTN was lower than that of the unaffected side, the right MC of the PTN and HC was lower than that of the left MC, the MC of the affected side of the left and right PTN without bilateral NVC was lower than that of the unaffected side.

Conclusions

By providing a method to analyze the morphology of the MC, we found that there is an asymmetry in the morphology of bilateral MC in the PTN and HC groups. It can be inferred that the flatness of the MC may be a cause of PTN.

Brain and spine melanotic schwannoma: A rare occurrence and diagnostic dilemma

PURPOSE

Melanotic schwannoma (MS) was formerly known as a rare variant of schwannoma. The behavior of MS is unpredictable, with a tendency for recurrence and metastasis. The purpose of this study was to illustrate the imaging characteristics of these rare and misdiagnosed tumors. The prognosis of MS is discussed, along with the importance of follow-up exams to assess for recurrence and metastasis. Furthermore, we compare our results with those previously published on MS in order to have a better understanding of this rare entity.

METHODS

Three MS cases were encountered between 2008 and 2015 at our institute. All available data were reviewed, including the clinical history, imaging findings, operative notes, and the histopathology results. A follow-up magnetic resonance imaging (MRI) scan was also reviewed up to 23 months post surgery to assess for recurrence.

RESULTS

Three cases of MS are included: one in the brain and two in the spine. The brain lesion was in the occipital region. The spine lesions were thoracic intramedullary and sacral intradural. All cases were hypointense on T2-weighted imaging. Gross total resection was achieved for all lesions without adjuvant therapy. To date, the brain lesion recurred 15 months after surgery.

CONCLUSIONS

MS is a rare and distinct entity rather than a variant of schwannoma, and it poses both diagnostic and management dilemmas. Although MS has characteristic MRI features, including T1 and T2 shortening, the preoperative diagnosis is always challenging. Accurate diagnosis is crucial for management planning, including long-term follow-up exams to assess for recurrence and metastasis.

Giant Melanotic Malignant Peripheral Nerve Sheath Tumor in the Pelvis: Contrast-Enhanced CT and 18F-FDG PET/CT Finding

Melanotic malignant peripheral nerve sheath tumor is an extremely rare tumor, which originates from the neural crest, and more than half the cases are associated with Carney complex (myxomas, spotty pigmentation, and endocrine abnormalities). Herein, we have presented a case of a melanotic malignant peripheral nerve sheath tumor, which is not associated with Carney complex. The patient underwent preoperative nonenhanced CT, contrast-enhanced CT, and F-FDG PET/CT scans, which showed a large pelvic tumor with heterogeneous enhancement and increased F-FDG uptake. Subsequently, the patient underwent complete resection of the tumor.