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Biomedical subjects

T W Shek

Publications and source records attributed to T W Shek.

At least 73 records · Page 4Linked to original sources
PubMed1997

Repeated hepatectomies for recurrent follicular dendritic cell tumour of liver: a case report.

Follicular dendritic cell tumour is a very rare tumour of unknown aetiology. We report a case of follicular dendritic cell tumour of liver which was treated with extended right hemihepatectomy but recurred twice in the remaining left lobe within 3 years. The recurrent tumours were removed by further liver resection. The mainstay of treatment for this rare tumour is surgical resection.

Adenocarcinoma, Follicular↗
PubMed1997

Magnetic resonance imaging of subcutaneous diffuse neurofibroma.

A 31-year-old woman presented with increasing pain and tenderness of a long-standing soft tissue mass on her back. MRI showed a network of interconnecting tubular areas, which were T1 isointense and T2 hyperintense relative to skeletal muscle, and displayed marked Gd-DTPA enhancement. The lesion was situated within the subcutaneous fat. Clinically and radiologically, this mass was considered to be a subcutaneous venous haemangioma. Histological examination of the excised mass showed a diffuse neurofibroma with ectatic vessels and entrapped adipose tissue. Similar MRI appearances of subcutaneous haemangioma and diffuse neurofibroma may result in failure to make the correct diagnosis and in inappropriate management.

Adult↗
PubMed1996

Lymphoepithelioma-like carcinoma of the thyroid gland: lack of evidence of association with Epstein-Barr virus.

Lymphoepithelioma-like carcinomas (LELC) occurring in sites derived from the primitive pharynx and foregut have been reported to show a strong association with Epstein-Barr virus (EBV), especially in the Oriental population. Primary lymphoepithelioma-like carcinoma of the thyroid is an extremely rare neoplasm which has been known under many different names, such as intrathyroidal epithelial thymoma, primary thyroid thymoma, carcinoma of the thyroid showing thymoma-like features, and carcinoma showing thymus-like differentiation (CASTLE). We report one such case in a Chinese woman, whose tumor was negative for EBV by in situ hybridization technique. This finding suggests that LELC of the thyroid may be biologically different from other LELCs, and that detection of EBV may aid in diagnosis when the LELC presents initially in lymph nodes or other metastatic sites.

Adult↗
PubMed1996

Lymphoepithelioma-like carcinoma of the skin.

The histopathological findings of two cases of primary lymphoepithelioma-like carcinoma (LELC) of the skin occurring in two elderly Chinese individuals are presented. Microscopically, they were well circumscribed and were composed of irregular nests of malignant epithelial cells in a background of reactive lymphoid cells including mature plasma cells. A focus of epithelial dysplasia was noted in the adjacent epidermis in one case, suggesting that the LELC might have originated from the overlying epidermis. The epithelial nature of the tumors was confirmed by cytokeratin staining. In situ hybridization for Epstein-Barr virus-encoded RNA (EBER) showed that the tumor cells were uniformly negative, although positive signals were detected in scattered background lymphocytes in case 1. Our results confirm the previous observation that LELC of skin is not related to Epstein-Barr virus, even in Chinese subjects. Nevertheless, such negative findings may prove to be of diagnostic value in excluding the alternative more common diagnosis of metastatic nasopharyngeal carcinoma, which is uniformly positive for EBER.

Aged↗
PubMed1996

Case report: lysosomal glycogen storage disease with normal acid maltase: an unusual form of hypertrophic cardiomyopathy with rapidly progressive heart failure.

A 14-year-old boy with mild mental retardation, myopathy, and nonobstructive hypertrophic cardiomyopathy (HCM) with clinical and histopathologic features consistent with lysosomal glycogen storage disease with normal acid maltase is described. The case illustrates the aggressive nature of the cardiomyopathy of this syndrome. This condition is associated with malignant ventricular arrhythmias, relentlessly progressive ventricular dilatation, dysfunction, and sudden death. It is important to recognize this unusual and malignant form of HCM to precipitate low early diagnosis by muscle biopsy. Patients with this condition would be excellent candidates for life-saving heart transplant as the myopathy and mental retardation are mild and nonprogressive. The underlying biochemical defect and mode of inheritance of this syndrome are unclear. However, a significant proportion are genetically related and thus, relatives may benefit from family screening.

Adolescent↗
PubMed1996

Follicular dendritic cell tumor of the liver. Evidence for an Epstein-Barr virus-related clonal proliferation of follicular dendritic cells.

Tumors of the follicular dendritic cell are uncommon, and most occur as primary lymph node tumors. We report a case of primary follicular dendritic cell tumor of the liver that was initially reported as an inflammatory pseudotumor. The neoplasm recurred as two separate tumor masses 30 months after complete resection of the "hepatic inflammatory pseudotumor." It showed a wide spectrum of morphologic features ranging from areas with fascicles of very bland spindle cells amidst a background population of lymphocytes, reminiscent of inflammatory pseudotumor, to areas of dispersed sheets of highly pleomorphic tumor cells with a relative paucity of reactive inflammatory cells. The diagnosis was confirmed by positive immunohistochemical staining with CD21, CD35, R4/23, and Ki-M4 and by ultrastructural demonstration of convoluted interdigitating cell processes joined by desmosomes. The background lymphocytes were oligoclonal, CD8-positive T cells. In situ hybridization for Epstein-Barr virus (EBV)-encoded RNA was positive in the tumor cells in the original and recurrent tumors. More importantly, the cells showed identical episomal clonal EBV on Southern blot analysis, implying that the initial and recurrent tumors are due to clonal proliferation of EBV-positive neoplastic follicular dendritic cells. The tumor cells expressed latent membrane protein but not EBV-encoded nuclear antigen 2 (EBNA2) or ZEBRA. Such gene expression is very similar to that of Hodgkin's disease and nasopharyngeal carcinoma. The strong expression of latent membrane protein restricted to the tumor cells and the clonality of the EBV suggest that the virus may be involved in the pathogenesis of this tumor and not present merely as a "bystander."

Adult↗
PubMed1996

Inflammatory cell-rich gastrointestinal autonomic nerve tumor. An expansion of its histologic spectrum.

Gastrointestinal autonomic nerve (GAN) tumor is an uncommon neoplasm of the gastrointestinal tract. Its histologic appearance is similar to other gastrointestinal stromal tumors. Ultrastructural demonstration of neural differentiation is required for its definitive diagnosis. Recently, we encountered two examples of GAN tumor that occurred in the body of the stomach and the cervical esophagus; the latter site has never been reported previously. These tumors showed unequivocal evidence of neural differentiation ultrastructurally, confirming the diagnosis of GAN tumor. Histologically, they were composed of swirling fascicles of spindle cells as well as a minor component of epithelioid cells, similar to that described previously. In addition, a cuff of lymphoid cells was noted at the peripheral part of both tumors and a scattering of mature plasma cells, lymphocytes, and foam cells was intermingled with the tumor cells. Such histologic features have not been described hitherto and can potentially be misinterpreted as features of inflammatory pseudotumor, inflammatory fibrosarcoma, or follicular dendritic cell tumor. There is a lack of CD34 expression in both tumors, but it would be premature to draw any conclusions about the potential usefulness of this observation.

Adult↗
PubMed1996

Germ cell tumour as a diagnostic pitfall of metastatic carcinoma.

AIM: Testicular germ cell tumours may present as metastases in cervical lymph nodes, yet the primary tumours remain clinically occult. The aim of the study is to alert pathologists and clinicians to this uncommon but important presentation and highlight the clues and the diagnostic adjuncts to its correct diagnosis. METHODS: The clinical, cytological, histological, and immunohistochemical features of two patients with germ cell tumour initially presenting as cervical lymphadenopathy were described and analysed. RESULTS: Both patients were young adult males, who were found to have metastatic undifferentiated carcinoma on fine needle aspiration of the enlarged cervical lymph nodes. The tumour cells in both cases were positive for placental alkaline phosphatase (PLAP) and negative for epithelial membrane antigen (EMA). CONCLUSIONS: Clinicians and pathologists should be aware of the possibility of germ cell tumour when encountering a young adult male with metastatic poorly differentiated carcinoma. Positivity for PLAP and negativity for EMA are helpful adjuncts in arriving at the correct diagnosis.

Adult↗
PubMed1996

Paclitaxel-induced cardiotoxicity. An ultrastructural study.

The ultrastructural appearance of the myocardium in a fatal case of paclitaxel-induced cardiotoxicity is reported, which includes swelling of the sarcoplasmic reticulum, loss of myofibrils, and accumulation of lipofuscin as well as laminated myelinoid figures. Such changes are very similar to those seen in anthracycline-induced cardiotoxicity and may suggest a pathogenetic final common pathway. While endomyocardial biopsy is a recognized means of monitoring anthracycline-induced cardiotoxicity, whether more liberal use of endomyocardial biopsy can prevent fatal cases of paclitaxel-induced cardiotoxicity needs to be further assessed.

Antineoplastic Agents, Phytogenic↗
PubMed1995

Melanotic oncocytic metaplasia of the nasopharynx.

Two cases of melanotic oncocytic metaplasia occurring in the nasopharynx are reported. One presented with serous otitis media and the other with tinnitus. Nasoscopic examination revealed a small brown nodule obstructing the Eustachian tube in both cases. While oncocytic metaplasia of the nasopharynx is not too uncommon, melanin pigmentation of the nasal or nasopharyngeal mucosa is very rare. To our knowledge, their combination has not been described.

Aged↗
PubMed1993

Inflammatory pseudotumor of the liver. Report of four cases and review of the literature.

In this report, we describe four cases of inflammatory pseudotumor of the liver and review the literature of this disease entity. The age of our patients ranged from 31 to 35 years (mean, 33 years). Two had fever, weight loss, and upper abdominal pain. The other had an incidental 1-cm nodule in the liver found during left hemihepatectomy for recurrent attacks of cholangitis. The preoperative clinical diagnoses in the former two cases were hepatocellular carcinoma. The patients had unremarkable recovery after resection. Grossly, the tumors showed a variegated appearance with areas of hemorrhage and necrosis and resembling hepatocellular carcinoma. Microscopically, the tumors were composed of a polyclonal population of reactive plasma cells and abundant plump spindle cells. The latter expressed vimentin but stained negatively for actin, desmin, and myosin. Ultrastructurally, these plump spindle cells showed features of fibroblastic differentiation. Forty-seven cases of inflammatory pseudotumor of the liver have been reported, 35 in males and 12 in females (male-to-female ratio of 2.9). The patients had a wide age range (10 months to 83 years; mean, 37 years). The most common symptoms were fever, upper abdominal pain and a space-occupying lesion in the liver. Surgical excision was curative. A few patients responded to antibiotic and steroid treatment. The recognition and distinction of this entity from hepatocellular carcinoma and other malignant tumors is particularly important in order to avoid unnecessary extensive surgery.

Adult↗
PubMed1977

Synthesis of 5,6-dihydro-8(7H)-quinolinone thiosemicarbazones as potential antitumor agents.

5,6-Dihydro-8(7H)-quinolinone was synthesized and converted into thiosemicarbazones which could be considered to be semirigid analogues of the 2-formylpyridine thiosemicarbazone class of antitumor agents. The Z and E isomers were separated and identified by 1H NMR and UV. Although the compounds showed essentially no inhibitory activity against the enzyme alkaline phosphatase, several of these agents had demonstrable anticancer activity in mice bearing the P388 leukemia. The E-configuration analogues in general were slightly more active than their corresponding Z isomers.

Alkaline Phosphatase↗