Treatment of a Traumatic Leptomeningeal Cyst in an Adult with Fibrinogen-Based Collagen
A 28-year-old man presented with a growing soft mass on the vertex of his head; it had developed 5 months earlier. Sixteen months prior to this, the patient had been involved in an incident in which he had received a blow to the head. Initially, he had a small subgaleal hematoma but it disappeared by the following day. Patient did not visit hospital for the head trauma; thus, head computed tomography (CT) and X-rays were not performed at that time.\nTwo years ago, the patient was diagnosed with bipolar disorder, and it was because of this that he underwent a physical examination and EEG for evaluation of his psychological state one month after the incident. At this time, no mass was detected on his scalp. Also, he did not feel the mass on the scalp. It was not until 8 months later that a mass developed, which continued to grow. The patient experienced no associated symptoms, and the mass was not tender to touch. A plain X-ray revealed a round 5×5 cm area of lucency in the posterior parietal bone with adjacent skull erosion. Upon enhanced CT examination of the head, a bony defect involving both the inner and outer table of the cranium was observed close to the superior sagittal sinus. A well-defined mass, 5 cm in diameter, was nested within the defect (). There were no enhancing lesions inside the cyst, and the rest of the brain parenchyma was free from notable anomalies. Magnetic resonance imaging (MRI) of the lesion was hypointense on T1-weighted images and hyperintense on T2-weighted images, indicating that a cystic lesion was propagating through the defect and slightly compressing the adjacent brain.\nFollowing this, the patient underwent surgery. A skin flap was created close to the lesion by making an incision down to the galea. The underlying lesion was pulsatile. The galeal layer was then dissected from the cyst, which exposed the cystic membranes. These membranes protruded through the bone defect and contained a clear fluid. The dura around the bone defect was thin and fragile.\nUsually, dura is sutured in a watertight manner with artificial dura, such as lyophilic dura. However, due to the close proximity of the defect to the sagittal sinus, we chose instead to place fibrinogen-based collagen fleece (TachoComb®) over the dural defect in order to reduce the risk of injuring or perforating the sinus. Six pieces of fibrinogen-based collagen fleece, cut to a size of 1×3 cm, were thus placed over the dural defect in a partially overlapping manner. The gluing surface of the fibrinogen-based collagen fleece was attached to the dural defect, exceeding the margins by about 0.5 cm. A wet patty was then applied over the defect and gently compressed. After the patty was removed, any extra seepage of blood was prevented by the application of an additional layer of fibrinogen-based collagen fleece on top of the existing layer (). The outer table of the skull was reconstructed.\nThe day after surgery, the patient remained asymptomatic and displayed good cosmetic results. Histologic findings revealed that the cyst was lined by meningothelial cells resting on a layer of supporting fibrous tissue. The walls of the cyst were infiltrated with mild chronic inflammatory cells and displayed vascular congestion. The cyst surface was focally lined with flattened epithelial cells, and the underlying brain tissue had become gliotic. The presence of chronic inflammatory cells and hemosiderin-containing macrophages suggested traumatic etiology (). Thirteen months later, a follow up brain CT scan of the patient revealed no recurrent cystic mass ().