Primary spinal cord glioblastoma multiforme: a single-center experience.

INTRODUCTION: Primary spinal glioblastoma (GBM) are very rare tumors of the spinal cord, with dismal prognosis and their exact management is controversial. We attempt to formulate treatment guidelines for these extremely rare tumors based on our institutional experience and a comprehensive review of the literature. MATERIALS AND METHODS: In this retrospective study from 2008 to 2020, all the patients diagnosed with primary spinal GBM who underwent surgery at our institution were included. Clinical data were retrieved from case files, outpatient records and telephonic follow-up. Data on postoperative chemoradiation was noted in all the patients. The final diagnosis of spinal GBM was confirmed as per the histopathology reports. Patients who could not be followed up and those with prior history of cranial GBM were excluded from the study. RESULTS: Nine patients were followed up and a median survival of 11 months was noted. Chemotherapy with TMZ and radiotherapy to the whole craniospinal axis significantly improved survival in these patients. The extent of surgical resection was not shown to be significant. Intracranial metastasis was the leading cause of mortality in such patients. Three patients developed documented intracranial metastasis during the course of the disease. CONCLUSIONS: Low threshold must be kept in mind in diagnosing patients with high-grade spinal cord intramedullary tumors in view of the rapidly progressing nature of the disease. In case of positive histopathological diagnosis of spinal GBM, the whole craniospinal axis should be imaged and any cranial metastasis which was originally missed during initial workup could be given appropriate radiotherapy.

Recent updates in thoracic SMARCA4-deficient undifferentiated tumor.

Germline inactivating mutations in SMARCA4 (SWI/SNF-related, matrix-associated, actin-dependent regulator of chromatin, subfamily A, member 4) gene encoding for BRG1 (Brahma related gene-1) are the molecular drivers in small cell carcinoma of ovary, hypercalcemic type (SCCOHT) and in malignant rhabdoid tumors (MRT) that occur in the context of rhabdoid tumor predisposition syndrome-type 2. Somatic SMARCA4 mutations and/or loss of BRG1 have been identified in a variety of adult-onset epithelial and mesenchymal neoplasms. Among thoracic tumors, these include subsets of smoking-related non-small cell lung carcinoma (NSCLC) and a relatively rare, newly recognised tumor entity: thoracic SMARCA4-deficient undifferentiated tumor (SMARCA4-UT). Less than 100 cases of SMARCA4-UT have been reported to date. They present as large compressive and infiltrative mediastinal, lung and/or pleural masses in middle-aged male smokers. They are undifferentiated tumors composed of sheets of small/epithelioid and/or rhabdoid tumor cells variably expressing epithelial markers and consistently showing loss of BRG1 and the closely related protein, Brahma (BRM). Frequent expression of stem cell markers (SOX2, CD34, SALL4) is noted. Despite gene expression profiles similar to MRTs and SCCOHT, they show striking genomic overlap with SMARCA4-mutant NSCLC with frequent TP53, STK11, KEAP1, and KRAS mutations, high tumor mutation burden (TMB), and presence of smoking related molecular signatures in tumor cells. SMARCA4-UT show uniformly poor survival and are irresponsive to conventional therapies. Immunotherapy responses are variable but promising, although PDL1 expression appears to be of poor predictive value. Drugs exploiting genetic and epigenetic mechanisms of SMARCA4 antagonism hold promise for future targeted therapies.

Ependymosarcoma harboring C11orf95:RELA fusion transcript: Report of two cases and review of the literature.

Ependymoma is a relatively rare glial tumor of the central nervous system that arise from the cells lining the ventricles and central canal of the spinal cord. Ependymosarcoma (ES) is a newly introduced tumor entity of uncertain prognosis characterized by a rare phenomenon of a malignant mesenchymal transition arising within an ependymoma. ESs are surgically challenging tumors for diagnosis and therapy with a high incidence of morbidity and mortality. Here, we report two diagnostically challenging cases of primary ES in a 25-year-old female and a 17-year-old male. Both the cases presented with progressive and sequential neurological deficits over a period of five to eight months, and histological examination revealed a biphasic gliomesenchymal architecture comprised of anaplastic ependymomatous and sarcomatous components. Molecular genetic analysis revealed the presence of type 1 C11orf95:RELA fusion transcript. To date, 22 cases of ES have been reported in the literature, and only one case harbored type 1 C11orf95:RELA fusion transcript.

C19MC amplification and expression of Lin28A and Olig2 in the classification of embryonal tumors of the central nervous system: A 14-year retrospective study from a tertiary care center.

INTRODUCTION: CNS embryonal tumors (CET) other than medulloblastomas (MB) and atypical teratoid/rhabdoid tumors (AT/RTs), previously designated as 'central nervous system primitive neuroectodermal tumors' ('CNS PNETs'), are a heterogenous subset of tumors with poorly defined diagnostic criteria. Other than the subset of embryonal tumor with multilayered rosettes (ETMR) defined by C19MC amplification, most CETs are diagnosed by exclusion of other molecularly defined entities and histological mimics including MB, AT/RTs, and high-grade gliomas, and termed as CET, not otherwise specified (NOS) in the 2016 WHO classification. AIM: To reclassify 'CNS PNETs' as per WHO 2016, and estimate the true proportion of CET, NOS in a tertiary healthcare setting, and to evaluate the diagnostic utility of C19MC amplification, Lin28A and Olig2 expression in the subclassification of CETs. METHODS: Previously diagnosed cases of 'CNS PNETs' (2002-2016) were first evaluated by immunohistochemistry (IHC) for MIC2, RelaA, L1CAM, IDH1R132H, H3K27M, H3G34R, H3G34V, INI1, and BRG1 proteins and by fluorescence in-situ hybridization (FISH) for EWSR1 translocation to exclude histological mimics. The selected CETs (case cohort) and 79 histological mimics (comparison cohort) comprising of MB, AT/RT, pineal parenchymal tumors, Ewing sarcoma, esthesioneuroblastoma, intraocular medulloepithelioma, and H3G34R mutant high-grade glioma were subject to IHC for Olig2 and Lin28A, and FISH for C19MC amplification. RESULTS: Twenty-two cases of 'CNS PNETs' were retrieved, all of which were negative for the first panel of markers and showed retained INI-1/BRG1 expression. Three of them (3/22, 13.6%) showed C19MC amplification (ETMR, C19MC-altered) with ETMR histology, Lin28A positivity, and Olig2 negativity. Among the remaining 19 CETs, one showed medulloepithelioma histology (Medulloepithelioma, NOS) and remaining were non-descript small round cell tumors (CET, NOS), all negative for Lin28A. Olig2 was positive in only 3 CETs (13.6%), all being CET, NOS. All tumors in the comparison cohort were negative for C19MC amplification, Lin28A and Olig2 except for 27% of ATRTs that were Lin28A positive. CONCLUSION: ETMR, C19MC-altered constitute less than 14% of CETs, with majority remaining uncharacterized as CET, NOS. Lin28A is 100% sensitive for the detection of C19MC amplification; however, its specificity is limited by its expression in ATRTs. Olig2 expression is seen only in a small subset of CET, NOS and is of limited diagnostic utility.

Metastatic lesions of atrial myxoma. A pathologist can clinch them all.

Atrial myxomas are the most common primary benign cardiac tumors. The embolization of tumor particles is not infrequent, and in nearly half of them, the cerebral arteries are affected, usually leading to embolic ischemic stroke. Formation of intracranial aneurysms, development of parenchymal brain metastasis, and intracerebral hemorrhage due to ruptured aneurysms are rarer. Diagnosis of such lesions in a previously undiagnosed case of myxoma may be challenging for a pathologist. Herein, we present two patients of cardiac myxoma with varied neurological manifestations and their pathological findings.

Comparison of laboratory-developed test & validated assay of programmed death ligand-1 immunohistochemistry in non-small-cell lung carcinoma.

Background & objectives: Inhibitors of immune checkpoint regulators, programmed death-1 (PD-1) and programmed death ligand-1 (PD-L1), improve outcome in advanced non-small-cell lung carcinoma (NSCLC). Tumours expressing PD-L1 protein are more likely to benefit from this targeted therapy. Multiple concurrent clinical trials evaluating different anti-PD-1/PD-L1 therapies have validated five different immunohistochemistry (IHC) assays using varied antibody clones and staining conditions. This study was aimed at identification of a single harmonized PD-L1 assay for tumour tissue conservation and cost-effectiveness in patients with NSCLC. Methods: The performance of low-cost, manual, laboratory-developed technique (LDT) PD-L1 IHC assay using the easily available SP142 clone was compared with trial validated Ventana SP263 IHC performed on automated Ventana staining platform on tumour sections of NSCLCs. Results: Eighty cases of NSCLC were included. SP263 and SP142 stained both tumour cells and immune cells. The concordance rate of tumour cell staining was about 76 per cent, with SP263 detecting more tumour cells in 16 per cent of cases. The concordance rate of immune cell staining was only 61 per cent, with SP142 detecting more immune cells in 24 per cent of cases. The sensitivity, specificity, positive and negative predictive values of manual SP142 LDT assay against gold standard SP263 Ventana assay were 70, 94, 86 and 86 per cent, respectively, at positivity thresholds of ≥1 per cent tumour cell staining. Interpretation & conclusions: The study findings suggested that LDT using SP142 clone showed only moderate concordance with SP263 Ventana assay, and the two assays were not interchangeable. More such validation studies need to be done to generate information that can complement patient therapy in cases of NSCLC.

Endobronchial ultrasound-guided transbronchial needle aspiration cytology in patients with known or suspected extra-pulmonary malignancies: A cytopathology-based study.

BACKGROUND: Endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA) is the primary modality for mediastinal lymph node staging in lung carcinoma. We aimed to evaluate its utility in extra-pulmonary malignancies (EPM). METHODS: Database search of EBUS-TBNA aspirations (2013-2017) done in patients with known/suspected EPMs and mediastinal lymphadenopathy/masses was performed. All archived cytology/histology material was reviewed and categorised as positive, negative and unsatisfactory. RESULTS: The selected 139 patients included 100 patients with known EPMs, 11 patients with known lymphoma, and 28 patients with suspected EPM of unknown primary. EBUS-TBNA was adequate in 110 patients (79%), including 21 patients who yielded only reactive lymphoid tissue. Satisfactory blood clot cores were obtained in 34 patients and contributed significantly to diagnosis and ancillary testing. Metastasis was detected in 45 patients with known EPM, predominantly originating from a known primary in the breast in females (56%) and squamous cell carcinomas of head and neck in males (60%). Granulomatous lymphadenopathy was identified in 16 patients with known EPM (16%). Lymphoma relapse and granulomatous lymphadenopathy were identified in three and four patients with known lymphoma, respectively. In patients with suspected EPM of unknown primary site, malignancy was confirmed in 21 patients, predominantly representing metastatic adenocarcinomas (n = 5) and neuroendocrine neoplasms (n = 5). Immunocytochemistry was performed in 16 of these cases and aided in characterisation of primary site/type of tumour in 12 cases. CONCLUSION: EBUS-TBNA is efficient for screening mediastinal lymph nodes/masses for malignancy in EPMs. Procuring sufficient material for ancillary testing would improve diagnostic accuracy and reduce need for resampling.

Prognostic stratification of muscle invasive urothelial carcinomas using limited immunohistochemical panel of Gata3 and cytokeratins 5/6, 14 and 20.

BACKGROUND: Genomic studies have delineated distinct molecular subgroups of urothelial carcinomas whose prognostic impact extends beyond traditional stage and grade groupings. The 'basal' subgroup shows increased gene expression levels of KRT5, KRT6, and KRT14 and low expression levels of GATA binding protein 3, and is associated with an extremely poor outcome. Identification of this subset is necessary for improved patient management and research on targeted therapies. We aimed to assess the prognostic utility of immunohistochemistry (IHC) for basal markers: cytokeratin 5/6 (CK5/6) and 14 (CK14), and luminal markers: cytokeratin 20 (CK20) and Gata3 in muscle invasive urothelial carcinomas (MIBC). MATERIALS AND METHODS: Study was of retrospective design (2014-2017). All chemotherapy naïve patients of MIBC undergoing radical cystectomy were included. IHC was performed on formalin fixed paraffin-embedded whole tumor sections. RESULTS: Among 40 cases of MIBC included, 45% (18/40) were positive for one or both basal markers, 37.5% (15/40) were positive for one or both luminal markers, while 15% (6/40) were positive for both basal and luminal markers. One case did not express any of the four markers. MIBCs expressing only basal markers presented at an advanced stage with frequent squamous differentiation and showed a trend towards shorter overall survival. Gata3+ MIBCs showed the best outcome irrespective of expression of other markers, while CK14+/Gata3- MIBCs were associated with worst outcomes. Gata3-/CK14- MIBCs showed intermediate survival outcomes. CK5/6, CK20 and p53 expression did not significantly correlate with outcome. CONCLUSION: IHC for Gata-3 and CK14 stratified MIBC into distinct prognostic subsets.

C11orf95-RELA fusions and upregulated NF-KB signalling characterise a subset of aggressive supratentorial ependymomas that express L1CAM and nestin.

Ependymomas (EPN) show site specific genetic alterations and a recent DNA methylation profiling study identified nine molecular subgroups. C11orf95-RELA and YAP1 fusions characterise the RELA and YAP1 molecular subgroups, respectively, of supratentorial (ST)-EPNs. Current guidelines recommend molecular subgrouping over histological grade for accurate prognostication. Clinicopathological features of ST-EPNs in correlation with C11orf95-RELA and YAP1 fusions have been assessed in only few studies. We aimed to study these fusions in EPNs, and identify diagnostic and prognostic markers. qRT-PCR and Sanger Sequencing for the detection of C11orf95-RELA, YAP1-MAMLD1 and YAP1-FAM118B fusion transcripts, gene expression analysis for NFKB1, and immunohistochemistry for p53, MIB-1, nestin, VEGF, and L1CAM were performed. 88 EPNs (10-Grade I and 78-Grade II/III) from all sites were included. RELA fusions were unique to Grade II/III ST-EPNs, detected in 81.4% (22/27) and 18.5% (5/27) of pediatric and adult ST-EPNs respectively. ST-EPNs harbouring RELA fusions showed frequent grade III histology (81.5%), clear cell morphology (70.3%), upregulated NFKB1 expression, MIB-1 labelling indices (LI) ≥ 10% (77.8%), and immunopositivity for nestin (95.7%), VEGF (72%), L1CAM (79%), and p53 (64%). Presence of RELA fusions, L1CAM immunopositivity and MIB-1 LI ≥ 10% associated with poor outcome. L1CAM showed 81% concordance with RELA fusions. YAP1-MAMLD1 fusion was identified in a single RELA fusion negative adult anaplastic ST-EPN. RELA fusions are frequent in ST-EPNs and associate with poor outcome. L1CAM is a surrogate immunohistochemical marker. RELA fusion positive ST-EPNs strongly express nestin indicating increased stemness. Further evaluation of the interactions between NFKB and stem cell pathways is warranted.

Cell blocks in cytopathology: An update.

The cell block (CB) offers many advantages over other cytological preparations, particularly for immunocytochemical and molecular testing. However, inconsistent cellularity remains the most common reason for dissatisfaction among cytopathologists. In recent years, there has been a surge in the demand for CBs imposed by the increasing number of minimally invasive procedures performed to obtain material for diagnostic, prognostic and predictive purposes from advanced stage cancer patients. However, routine preparation of CBs significantly increases laboratory work load, operating cost and sample turn-around time. The objectives of our review were to: (a) identify scenarios where a CB is likely to improve diagnostic yield; (b) optimise CB preparatory methods; and (c) understand the factors influencing the success and validity of ancillary testing on various types of CBs. We performed an extensive literature search on CBs in cytology on internet search engines using the following keywords: cell block, cytoblock, cytology, cytopathology, methods, preparation, fixatives, diagnostic yield, ancillary and molecular studies. New CB methods, improvisations of previous CB methods, their utility for diagnosis, immunocytochemistry and molecular testing, and role in predictive biomarker testing are discussed in this review. CBs of good quality and cellularity outperform other cytology preparations in their reliability and versatility for ancillary testing. With many CB methods described in the literature, each with specific advantages and limitations, laboratories may choose to use one or more of the methods depending upon their infrastructure, expertise and workload.

Pompe disease: An Indian series diagnosed on muscle biopsy by ultrastructural characterization.

Pompe disease (PD) is a lysosomal storage disorder characterized by glycogen accumulation in muscle, with infantile-onset (IOPD) and late-onset (LOPD) types. Nineteen cases of PD were diagnosed over a 14-year period on muscle biopsy by ultrastructural examination. Pools of glycogen (intralysosomal and cytoplasmic) and excessive phagocytosis were seen in myofibers on electron microscopy. Glycogen was noted in endothelial cells in IOPD. Although PD accounts for a small fraction of muscle diseases, timely accurate diagnosis is imperative as it is treatable. Ultrastructural examination is necessary to confirm the diagnosis in cases with non-diagnostic light microscopic features, especially in adult LOPD patients.

Study of ß-catenin and BRAF alterations in adamantinomatous and papillary craniopharyngiomas: mutation analysis with immunohistochemical correlation in 54 cases.

Craniopharyngiomas (CP) are rare benign epithelial tumors, with two histological variants, namely the adamantinomatous variant (ACP) and the rarer papillary variant (PCP). They are locally infiltrative and surgically challenging tumors with severe long term morbidity. CTNNB1 mutations with ß-catenin immunopositivity and BRAFV600E mutations with anti-VE immunopositivity have been recently described in ACPs and PCPs respectively. We aimed to study BRAF and CTNNB1 gene mutations in CPs operated at our institute, and correlate it with clinicopathological parameters including histopathology and immunohistochemistry (IHC) for proteins VE-1 and ß-catenin. A total of 54 CPs diagnosed over 3-year duration were included. IHC for ß-catenin and VE-1 proteins, and Sanger sequencing for CTNNB1 (exon 3) and BRAF (exon 15) genes were performed. CTNNB1 mutations were identified in 63% (27/43) of ACPs while nuclear immunopositivity for ß-catenin was observed in 79% (34/43) of them. Seven ACPs showed ß-catenin immunopositivity in the absence of mutations. BRAFV600E (p.Val600Glu) mutations were observed in 57% of PCPs (4/7), while cytoplasmic immunopositivity for anti-VE1 antibody was observed only in 43% of PCPs (3/7), all of which also harboured BRAFV600E mutations. The mutations and IHC staining patterns of ACPs and PCPs were non-overlapping. Four cases with uncertain histological pattern could be subcategorised into specific variants only following mutation analysis/IHC. The identification of hallmark molecular signatures in the two CP variants holds promise for alternate improved treatment modalities, emphasizing the need for sub-categorization in routine histopathology reporting. IHC for ß-catenin and targeted sequencing for BRAFV600E serve as useful adjuncts.

Progressive multifocal leukoencephalopathy in a 44-year old male with idiopathic CD4+ T-lymphocytopenia treated with mirtazapine and mefloquine.

Progressive multifocal leukoencephalopathy (PML) is an opportunistic viral infection of the central nervous system caused by the reactivation of John Cunningham virus (JCV) in immunocompromised patients, most commonly in human immunodeficiency virus (HIV) infection, and less commonly in those receiving various immunosuppressive regimens. Prognosis of untreated PML is grave and the mainstay of treatment is the reversal of immunosuppression, usually by institution of antiretroviral drugs in HIV patients and cessation of immunosuppressive therapies in others. PML is increasingly being reported in those with minimal or occult immunosuppression. A small fraction of these patients meet the criteria for idiopathic CD4+ T-lymphocytopenia (ICL) after exclusion of all secondary causes of lymphocytopenia, including HIV. A 44-year-old previously healthy male presented with clinical and radiological features suggestive of PML. Cerebrospinal fluid samples were repeatedly negative for JCV. Immunohistochemistry on brain biopsy eventually confirmed PML. Despite extensive work-up, the only abnormality detected was an unexplained and persistently low absolute CD4+ T-lymphocyte count. Based on the limited available literature on the treatment of non-HIV PML, he was treated with a combination of mirtazapine and mefloquine with clinical improvement. Non-HIV PML remains relatively uncommon, and PML as a presenting feature of ICL is rare. It is important to document and follow these patients to be able to assess the relative risks associated with various causes and formulate effective therapeutic strategies.

Evaluation of chromosome 1q gain in intracranial ependymomas.

Ependymomas are relatively uncommon gliomas with poor prognosis despite recent advances in neurooncology. Molecular pathogenesis of ependymomas is not extensively studied. Lack of correlation of histological grade with patient outcome has directed attention towards identification of molecular alterations as novel prognostic markers. Recently, 1q gain has emerged as a potential prognostic marker, associated with decreased survival, especially in posterior fossa, high grade tumors. Cases of intracranial ependymomas were retrieved. Tumors were graded using objective criteria to supplement WHO grading. Fluorescence in situ hybridization for 1q gain was performed on formalin-fixed paraffin embedded sections. Eighty-one intracranial ependymomas were analyzed. Pediatric (76%) and infratentorial (70%) ependymomas constituted the majority. 1q gain was seen in 27 cases (33%), was equally frequent in children (34%) and adults (32%), supratentorial (37%) and infratentorial (32%) location, grade II (33%) and III (25%) tumors. Recurrence was noted in 24 cases and death in 7 cases with 5-year progression-free and overall-survival rates of 37% and 80%, respectively. Grade II tumors had a better survival than grade III tumors; histopathological grade was the only prognostically significant marker. 1q gain had no prognostic significance. 1q gain is frequent in ependymomas in Indian patients, seen across all ages, sites and grades, and thus is likely an early event in pathogenesis. The prognostic value of 1q gain, remains uncertain, and multicentric pooling of data is required. A histopathological grading system using objective criteria correlates well with patient outcome and can serve as an economical option for prognostication of ependymomas.

ATRX loss in glioneuronal tumors with neuropil-like islands indicates similarity to diffuse astrocytic tumors.

Glioneuronal tumor with neuropil-like islands (GTNI) is a rare, recently described neoplasm, whose pathogenesis has not been studied extensively. The role of ATRX mutations, a class-defining alteration in diffuse astrocytic neoplasms, has not been assessed in GTNIs previously. We therefore aimed to assess the status of ATRX, along with IDH1, 1p/19q and p53, in cases of GTNI in order to evaluate the molecular profile of these tumors. All cases of GTNI diagnosed at our Institute were retrieved and clinicopathological features were reviewed. Immunohistochemistry for ATRX, IDH1 and p53 was performed. We identified four cases of GTNI, majority of which occurred in young adults. Loss of ATRX immunoexpression, a surrogate marker for ATRX mutation, was seen in all four cases. All cases were immunopositive for p53, while IDH1 positivity was seen in all three cases assessed. 1p/19q codeletion was absent in the three cases analyzed. These results indicate that the molecular pathogenesis of GTNIs similar to that of diffuse astrocytic tumors. Further, the loss of ATRX expression is seen in both the glial as well as neuronal components, indicating that both arise from the same tumor stem/progenitor cell and that the latter may be a metaplastic change. Thus, loss of ATRX immunoexpression, shown for the first time in these tumors, along with immunopositivity for p53 and IDH1, indicates that these tumors are molecular astrocytomas, and their clinical behaviour is likely to recapitulate that of ATRX-mutant and IDH-mutant diffuse astrocytomas of the same grade.

C11orf95-RELA fusion present in a primary intracranial extra-axial ependymoma: Report of a case with literature review.

Ependymomas are gliomas that recapitulate the ependymal cells microscopically and ultrastructurally. They commonly occur along the ventricular surfaces and central canal of the brain and spinal cord. Intracranial extra-axial ependymoma (IEAE) is a rare entity and is commonly misdiagnosed clinically and radiologically as a meningioma. The histogenesis of such IEAEs is obscure. A novel recurrent oncogenic fusion involving the C11orf95 and RELA genes was recently described in supratentorial ependymomas. A 9-year-old girl presented with a dural based parafalcine mass that, in addition to exhibiting classical immunohistochemical features of an ependymoma, also demonstrated C11orf95-RELA fusion, characteristic of supratentorial ependymomas. We suggest that IEAEs share their histogenesis with their intra-axial counterparts, arising either from dural extension of subcortical, subependymal rests or directly from ectopic dural rests.

Primary intra-osseous myoepithelioma of phalanx mimicking an enchondroma.

Myoepitheliomas (MEs) are uncommon tumours of the soft tissue with an intermediate biological behaviour and uncertain differentiation. Primary intra-osseous MEs are rare and occur predominantly in the axial and proximal appendicular skeleton in middle-aged patients. The morphological variation of the tumour cells and stromal metaplasia may cause considerable diagnostic confusion, especially when it occurs in an unusual location. A wide panel of immunohistochemical markers is required to exclude other histological mimics. A 37-year-old male presented with a recurrent swelling in the right middle finger for 1-month duration. Radiographic images showed an expansile, lytic, intra-osseous lesion with high signal intensity on T2W fat-suppressed MR images in the proximal phalanx of the right middle finger without cortical breach, highly suggestive of an enchondroma. Histopathology revealed a lobulated tumour comprising of polygonal to spindle cells in groups and cords in a chondromyxoid stroma. No cellular atypia was noted. The tumour cells were immunopositive for epithelial membrane antigen (EMA), p63, S100 and smooth muscle actin (SMA), compatible with the diagnosis of an intraosseous ME. The proximal phalanx of the right middle finger was excised, revealing a similar tumour, and the patient has been on regular follow-up for the last 18 months without any recurrence. Primary intra-osseous MEs are extremely rare, and this is the second reported occurrence in small bones. A differential diagnosis of ME should be kept for enchondroma-like lesions of the bone for proper histopathological assessment and accurate diagnosis. Documentation of such cases and follow-up will enhance our understanding of their clinical course and prognosis.

Monoclonal gammopathy of renal significance with light-chain deposition disease diagnosed postrenal transplant: a diagnostic and therapeutic challenge.

Patients with light-chain deposition disease (LCDD) frequently do not meet criteria for myeloma. In such cases, despite low tumor burden, the circulating monoclonal immunoglobulins cause renal damage, are responsible for post-transplant recurrence, and are rightly categorized as monoclonal gammopathy of renal significance (MGRS) requiring chemotherapy. A 65-year male with uncharacterized nodular glomerulopathy presented with proteinuria 3 years postrenal transplant. His allograft biopsies were diagnostic of light-chain deposition disease (likely recurrent), and in the absence of myeloma, he was labeled as MGRS. Based on the limited literature available, he was treated with bortezomib which resulted in normalization of serum-free light-chain ratios and resolution of proteinuria. He, however, later succumbed to complications of chemotherapy. This case highlights the diagnostic difficulties in LCDD, the importance of an accurate pretransplant diagnosis, and treatment of the malignant clone, in the absence of which post-transplant management of recurrence is challenging with poor outcomes.

Glycogen Storage Disorder due to Glycogen Branching Enzyme (GBE) Deficiency: A Diagnostic Dilemma.

Glycogen branching enzyme deficiency/Andersen disease can manifest with a spectrum of clinical phenotypes, making the diagnosis difficult. An 11-year-old Pakistani boy presented with a history of progressive weakness and delayed milestones. Echocardiography showed features of dilated cardiomyopathy. He was suspected to have congenital myopathy and was evaluated further. Muscle biopsy showed subsarcolemmal accumulation of basophilic material, which stained positively with Periodic acid-Schiff reagent (diastase-resistant). Ultrastructural examination revealed accumulation of structurally abnormal forms of filamentous glycogen, confirming the diagnosis as Andersen disease. As histopathological and immunohistochemical evaluation of muscle biopsies is not always diagnostic, ultrastructural examination may serve as a valuable adjunct in difficult cases.