Glial Fibrillary Acidic Protein Astrocytopathy: Review of Pathogenesis, Imaging Features, and Radiographic Mimics.

Glial fibrillary acidic protein (GFAP) astrocytopathy is a recently described autoimmune inflammatory disorder of the CNS characterized by the presence of specific antibodies targeting the intracellular filament protein in mature astrocytes. The pathogenesis is heterogeneous and poorly understood, with around 20%-34% of cases occurring as a paraneoplastic syndrome, most frequently associated with ovarian teratomas. It presents clinically as acute or subacute encephalomyelitis, and the diagnosis relies on imaging and detection of GFAP-Immunoglobulin (GFAP-IgG) in the CSF. Characteristic imaging findings include linear perivascular enhancement in the white matter extending in a radial pattern. Other imaging findings include periependymal enhancement, longitudinally extensive cord signal changes, intramedullary enhancement, optic neuritis, and papillitis. There is significant imaging overlap with other neuroinflammatory diseases like neuromyelitis optica spectrum disorder and lymphoproliferative conditions. GFAP astrocytopathy is characteristically responsive to steroids with, however, a significant rate of relapse. Currently, literature on this novel entity is limited with no established diagnostic criteria or standard treatment regimen. This comprehensive review explores the clinical, radiographic, and histopathologic aspects of GFAP astrocytopathy, shedding light on its complex nature and potential diagnostic challenges. The paper highlights the neuroimaging findings with a focus on differentiating GFAP astrocytopathy from other neuroinflammatory disorders.

Role of Digital Subtraction Angiography in the Preoperative Assessment of a Patient with a Petrosquamous Sinus: a Case Report.

We report a case of a 15-year-old Indian girl who presented with tinnitus, pain and ear discharge for one month and was preliminarily diagnosed with Chronic Suppurative Otitis Media (CSOM) with mastoiditis. She underwent a routine presurgical CT scan which revealed an aberrant vein, making it essential to exercise caution during surgery for CSOM. The aberrant vessel was identified as a Petrosquamous Sinus. A Petrosquamous Sinus is a persistent fetal vein that connects the transverse sinus with the retromandibular vein and may regress in an individual by birth. Its importance lies in the risk of haemorrhage it carries during otological surgeries. A Digital Subtraction Angiography proved to be a vital step in isolating the path of the vein for better visualisation of the course, thus giving a better idea about the anatomical relations of the vessel during the surgery. The tympanoplasty was performed with care to prevent damaging the vein. The patient had no complications in the postoperative period and made a quick recovery.

A Histopathology-based Assessment of Biological Behavior in Oral Hyalinizing Extraosseous Lesions by Differential Stains.

AIM: The assessment of hyalinization to determine aggressive behavior in oral pathological lesions is a scarcely researched field that requires further exploration. The current study aims to predict the biological behavior of oral hyalinizing extraosseous lesions (OHEOL) by employing four differential stains with clinicopathologic correlation. MATERIALS AND METHODS: The study was performed on retrospectively diagnosed formalin-fixed paraffin-embedded cases of salivary gland tumors (SGTs) (n = 13), benign soft tissue (BST) lesions (n = 24), and oral submucous fibrosis (OSMF) (n = 53). The hematoxylin and eosin-stained sections were analyzed for the severity of hyalinization (SOH). Differential stains periodic acid Schiff (PAS), Alcian blue, safranin O, and picrosirius red with polarizing microscopy were used to assess the components of hyalinized tissue. The SOH was correlated with differential staining characteristics and clinicopathologic features to analyze possible correlation with aggressive potential in BST, advancement of disease in OSMF, and recurrence in SGT. RESULTS: Intensity of picrosirius red stain significantly correlated with SOH of SGTs (p = 0.044). The intensity of PAS stain (p = 0.040), picrosirius red polarizing greenish-yellow color (p = 0.002), and pattern of distribution of picrosirius red (p = 0.023) significantly correlated with recurrence of SGTs. The intensity of differential stains increased with the SOH in BST lesions indicating their correlation with SOH. The intensity (p = 0.008) and pattern (p = 0.010) of Alcian blue staining and intensity of safranin O stain (p = 0.003) significantly correlated with SOH in OSMF. Picrosirius red polarizing color reddish and yellowish red (p = 0.002) significantly correlated with SOH distinguishing early and advanced OSMF. CONCLUSION: Picrosirius red and PAS stains are reliable indicators of SOH and recurrence potential in SGT. Alcian blue, safranin O, and picrosirius red polarizing colors enable detection of SOH and accurately distinguish early from advanced OSMF. CLINICAL SIGNIFICANCE: SOH can be considered as a histological predictor of aggressive biologic behavior in OHEOL. These findings will result in appropriate management protocols.

A Histopathology-based Assessment of Biological Behavior in Oral Hyalinizing Odontogenic Tumors and Bone Lesions by Differential Stains.

AIM: Odontogenic tumors (OTs) and bone lesions of the oral cavity present diverse histological features and varying clinical behavior that makes predicting their biologic behavior difficult. The research undertaken in the current study aims to predict the biological behavior of oral hyalinizing odontogenic and bone lesions (OHO-BL) for the first time by employing four differential stains with clinicopathologic correlation. MATERIALS AND METHODS: The study was performed on retrospectively diagnosed formalin-fixed paraffin-embedded cases of OTs (n = 53) and bone lesions (n = 10). The severity of hyalinization (SOH) was assessed from stained tissue sections. Polarizing microscopy was used to analyze hyalinization in tissues stained with differential special stains, namely periodic acid-Schiff (PAS), Safranin-O, Alcian Blue, and Picrosirius red. SOH was also analyzed for possible correlation with recurrence and clinicopathologic correlation in OHO-BL. RESULTS: Intense staining was observed with PAS, Alcian Blue, and Safranin-O in OTs with increased SOH with a statistical significance. Polarizing greenish yellow color correlated significantly with the recurrence potential of the OT group. Recurrence in individual lesions of the OT group showed a statistically significant association with SOH. Such individual correlation was not observed in bone diseases. CONCLUSION: PAS, Alcian Blue, Safranin-O, and Picrosirius red are reliable stains to assess hyalinization in OHO-BL. Picrosirius red-polarizing microscopy is a dependable tool for identifying recurrent odontogenic lesions. CLINICAL SIGNIFICANCE: SOH can be considered a histological predictor of aggressive biologic behavior in oral hyalinizing odontogenic lesions that can enable the surgeon to arrive at an appropriate management protocol.