RESUMO
Thymoma is the commonest epithelial neoplasm arising from thymus gland. Tumour is slow growing and in the absence of metastasis, surgery is the treatment of choice. Complete resection and bland morphology are important prognostic features. However, a significant proportion of these tumours tend to recur. These recurrent tumours, advanced thymomas and thymic carcinomas require platinum-based combination chemotherapy and radiotherapy. Efforts are being made to explore additional treatment modalities to control disease with the aim of improving survival. Number of thymoma cases worldwide is small in comparison to lung cancers. As a result, fewer studies have been carried out to enhance our understanding of molecular events responsible for the initiation, maintenance, and progression of thymomas. Inspite of this there are advances in understanding the pathology of thymic epithelial neoplasms including genetics, PD-L1 and molecular testing which has bearing on the prognosis, post-surgical management, and testing algorithm. Similar to pulmonary pathology, thymic epithelial tumours will require adequate tumour sampling to carry out ancillary testing. Mutational analytical tests include EGFR, RAS, BRAF, RET, AKT1, PIK3CA and T53 genes. If adequate sample is available (upto100 cells), PD-L1 testing should be considered for immunotherapy in recurrent/ advanced thymomas and thymic carcinomas. This list is likely to expand in future with increasing emphasis on molecular testing to support treatment with newer therapies.
RESUMO
This study analyzes the prevalence of T-cell non-Hodgkin's lymphoma (T-NHL) in a major referral center of Pakistan and its association with Epstein-Barr virus (EBV). Ninety-two cases of T-NHL were characterized on the basis of morphology, immunohistochemistry and genetic features. The prevalence of T-NHL was 22.2% of the total NHLs diagnosed during the eight years period (1992-1999). Polymerase chain reaction (PCR) technique was used to assess T-cell clonality in paraffin-embedded tissues of known T-NHL. Amplifiable DNA was isolated from all the cases, which were further studied for T-cell receptor (TcR)-beta, gamma, delta, and IgH chain gene rearrangements. Out of 92 cases 51 cases showed clonal product and 33 demonstrated polyclonal smear for beta, gamma, or delta chain genes, respectively, whereas 8 cases exhibited IgH chain gene rearrangement for FR2 region. This study demonstrated frequent presence of EBV in T-NHL (55.4%) by PCR, which were further tested for the localization of the virus by in situ hybridization (ISH). The extent of polymorphism in EBV genome was studied by single stranded conformation polymorphism (SSCP) technique for Bam HI E, K, N and Z regions. Hypervariability in Bam HI K, and N regions was noticeably higher compared to E or Z regions. In conclusion, our study demonstrated that the prevalence of T-NHL in Pakistan is slightly higher to that reported for Western communities. In addition, the frequency of EBV genome in T-NHL is intermediate as compared to other studies. No association was established between EBV variants differentiated on the basis of sequence heterogeneity in Bam HI K, N, E and Z regions with the manifestation of different subsets of T-NHL.
Assuntos
Infecções por Vírus Epstein-Barr/complicações , Herpesvirus Humano 4/genética , Linfoma de Células T/genética , Linfoma de Células T/virologia , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Criança , Células Clonais/patologia , DNA Viral/genética , Infecções por Vírus Epstein-Barr/epidemiologia , Feminino , Rearranjo Gênico , Genes Codificadores dos Receptores de Linfócitos T , Humanos , Cadeias Pesadas de Imunoglobulinas/genética , Linfoma de Células T/epidemiologia , Masculino , Pessoa de Meia-Idade , Paquistão/epidemiologia , Prevalência , Estudos RetrospectivosRESUMO
Primary pleomorphic adenoma of the lung is an uncommon condition. We present a case of primary pulmonary pleomorphic adenoma and its immunohistologic features. The presence of immunoreactivity to both anticytokeratin and antivimentin antibodies for its epithelial components is suggestive of a primary pulmonary lesion. Its high proliferation index and its immunoreactivity to tumor regulatory gene p16(INK4A) are features that, to our knowledge, have not been reported previously. They may have a role in the frequent recurrence of these tumors many years after their apparently complete excision. Detailed genetic investigation and long-term follow-up of this rare tumor will aid in the characterization of its biologic profile.