Meningiomas – transition from traditional histological grading to molecular profiling in WHO CNS5: A Review

Despite being the most common primary intracranial tumor, meningiomas are classified largely based on histological features. The current system of grading has been shown to be unsatisfactory due to its poor reproducibility as well as the considerable variability within grades. With the increasing availability of genomic and epigenomic profiling, several markers have been suggested to correlate with the location, histological subtype, and clinical behavior of meningiomas. These developments have enabled the development of targeted therapy, as well as individualized use of currently available adjuvant methods. These include copy number alterations (CNAs), specific genetic abnormalities (germline and sporadic), and genome-wide methylation profiles. In this review, we recapitulate the changes in the classification of meningiomas thus far, discuss the various histological subtypes recognized, and present the available literature on the genetic and epigenetic profiles of meningiomas. The recognition and further study of these markers have the potential to usher in an era of personalized therapy in the management of meningiomas, vastly improving outcomes as has been observed in the case of several other tumors.

Lymphomatoid granulomatosis: A case series from South India

Context: Lymphomatoid granulomatosis (LYG) is a rare B-lymphoproliferative disorder characterised by an angiocentric and angiodestructive pattern along with Epstein - Barr virus (EBV) association. It is one of the diagnostic challenges in lymphoma pathology. Deregulation of EBV immune surveillance is one of the narrated hypotheses in the literature. Extrapulmonary manifestations are rare with LYG. Morphological grading is done based on the number of EBV-positive B cells, which is useful to strategize treatment protocol. Aims: We report here a series of nine cases of LYG to discuss the clinical, histological, and immunohistochemistry findings. Settings and Design: This is the first case series from India in published literature. Subjects and Methods: We reviewed cases of LYG diagnosed at our center for the past 11 years (2006-2016). A total of nine cases were included in this study. Histomorphology was studied in conjunction with immunohistochemistry and clinical details. Cases without classical morphology and negative for EBV immunostain were excluded from the study. Results: There were nine patients in our study (7 males and 2 female; M:F ratio 3.5:1). The age of these patients ranged from 4 years to 57 years (mean age: 30 years). The most common site involved was the lung (4, 44%), followed by the skin (2, 22%), central nervous system (2, 22%) and lymph node (1, 11%). One patient had primary immunodeficiency. Another patient had undergone renal transplant 11 years before the development of the lesion. Angiocentricity and angioinvasion were appreciated in all nine cases (9/9) with necrosis in four cases (44%) and ill-defined histiocytic aggregates in three cases (33%). The histological features were as follows: Grade 1(4 cases, 44%), Grade 2(2 cases, 22%), and Grade 3(3 cases, 33%). Conclusion: LYG is a rare EBV driven angiodestructive disease with predominantly lung involvement as well as isolated extrapulmonary sites as seen in our study. It is often progressive and ultimately fatal in the absence of appropriate treatment. Grading of the lesion helps to initiate the appropriate treatment of choice.

Diagnostic validity of the Ki-67 labeling index using the MIB-1 monoclonal antibody in the grading of meningiomas.

BACKGROUND: About 10% of meningiomas behave aggressively and are graded atypical or malignant with important therapeutic and prognostic implications. Routine histological parameters are inconsistent in the assessment of their aggressive behavior. AIMS: The aim of this study was to find a threshold level of the MIB-1 labeling index (MIB-1 LI) with the highest diagnostic validity in predicting histological atypia in a meningioma. SETTING AND DESIGN: This was a retrospective study of all atypical and malignant meningiomas diagnosed at our center between January 1995 and June 2000 and which were identified from the General Pathology Registry. MATERIAL AND METHODS: These meningiomas were assessed histologically with respect to the individual criteria of atypia. They were categorized according to the WHO 2000 classification as benign, atypical and anaplastic meningiomas, WHO Grades I, II and III respectively and by immunohistochemical analysis using the MIB-1 monoclonal antibody. STATISTICAL ANALYSIS: The diagnostically useful cut-off level for the prediction of atypia was estimated by calculating the sensitivity and specificity of the MIB-1 LI at various levels and a receiver operated characteristic (ROC) analysis was performed. The correlation between the individual histological parameters was studied and the MIB-1 LI was obtained using Fisher's exact test. RESULTS: Of the 40 meningiomas studied 21 were benign, 16 atypical and 3 anaplastic. Atypical tumors had a higher MIB-1 LI than benign tumors, with diagnostic validity highest at a threshold of 7%, with a sensitivity of 0.86 and a specificity of 0.93, giving a likelihood ratio of 17. The MIB-1 LI correlated well with mitotic activity and the other individual criteria in the WHO 2000 definition of atypia in a meningioma. MIB-1 LI did not, however, correlate well with brain invasion. CONCLUSION: The MIB-1 LI has the highest validity in the diagnosis of atypia in meningiomas at a threshold level of 7%. The MIB-1 LI used in conjunction with histological features can help in making a recommendation regarding potentially aggressive behavior in meningiomas.

Hemorrhagic necrosis of pituitary adenomas.

A clinicopathological study of 41 cases of pituitary apoplexy in a series of 324 surgically treated pituitary adenomas is presented. In 23 patients, the predominant operative finding was hemorrhage with or without necrosis. However, there were 15 (37.7%) cases where pale, necrotic tissue with no evidence of hemorrhage was found at surgery. Pale, necrotic material was particularly found when there was a long interval between the acute clinical event and surgery. It is concluded that the pale, necrotic debris represents one stage in the resorption process of blood after hemorrhagic necrosis of pituitary adenomas. This entity needs to be kept in mind especially since the material closely resemble the pultaceous material seen in craniopharyngiomas and epidermoid cysts.

Endolymphatic sac tumor: a rare cerebellopontine angle tumor.

Endolymphatic sac tumors (ELST) are rare papillary tumors of the temporal bone. Previously named as aggressive papillary middle ear tumors, they have recently been shown to arise from the endolymphatic sac. They are a rare in cerebello-pontine angle (CPA). We present a case of an ELST who presented as a CPA tumor with hydrocephalus. He underwent a ventriculo-peritoneal shunt initially. On exploration of the CP angle, the tumor was found to be extremely vascular. He was re-explored following embolization, and a subtotal excision of the tumor was done. Extensive petrous bone infiltration and vascularity of the tumor makes total excision almost impossible with high risk of cranial nerve deficits, excessive blood loss and CSF leak. This tumor should be considered in the differential diagnosis of vascular CPA tumors which erode the petrous temporal bone. The relevant literature is reviewed.

Skull base chondroblastoma: a case report.

Chondroblastoma is a rare tumor of the skull. Temporal bone is the commonest site of involvement in the skull. We present a thirty one year old man who presented with painless swelling over the left temporal bone, which was near totally excised after preoperative embolization. Management of this unusual tumor and its complications are discussed.

Determination of Ki-67 labeling index in pituitary adenomas using MIB-1 monoclonal antibody.

Proliferative activity of 94 pituitary adenomas was assessed by the determination of the growth fraction, using MIB-1 monoclonal antibody in formalin fixed, paraffin embedded sections. This index was correlated with clinical and radiological evidence of invasiveness. The mean Ki-67 labeling index for all pituitary adenomas was 0.84% (range 0-17.45%). Hardy stage E tumours (1.44%) had a higher Ki-67 labeling index (LI) as compared with Hardy stage 0 tumours (0.36%). The difference in the Ki-67 labeling indices between invasive and non-invasive adenomas was not statistically significant. Hence, the Ki-67 labeling index is not a reliable indicator of invasiveness in pituitary adenomas.

Primary angiitis of the central nervous system: an ante-mortem diagnosis.

A rare case of primary angiitis of the central nervous system (PACNS) is reported with its clinical and magnetic resonance imaging (MRI) features. A 20-year-old girl presented with headache, projectile vomiting, unsteadiness of gait and urgency of micturition. She had left seventh nerve upper motor neuron type paresis, increased tone in all four limbs, exaggerated deep tendon reflexes, cerebellar signs, and papilloedema. Cerebrospinal fluid showed lymphocytosis with elevated protein and normal glucose level. Cerebral computerised tomographic scan and MRI showed bilateral diffuse asymmetric supra- and infra-tentorial lesions (predominantly in the supratentorial and left cerebrum). On MRI, the lesions were hyperintense on T2, and proton density-weighted images and hypointense on T1-weighted images. Based on the clinical findings of raised intracranial tension and MRI features, initial diagnoses of gliomatosis cerebrii, tuberculous meningitis, primary central nervous system lymphoma and chronic viral encephalitis were considered. PACNS was not included in the initial differentials and, an open brain biopsy was advised which established the definitive diagnosis.

Medullomyoblastoma: A case report.

Medullomyoblastoma is a rare tumour seen in childhood. We report a medullomyoblastoma occurring in the cerebellar vermis of a 4 year old boy. The light microscopic features, immunohistochemistry and histogenesis are described.