Biomedical subjects
Publications and source records attributed to J K Chan.
A case of a low-grade mucoepidermoid tumour showing an unusual pattern of extensive central keloid-like sclerosis is reported. The sparsity of tumour islands renders recognition of its neoplastic nature difficult. It is postulated that the sclerosis results from exaggerated post-inflammatory scarring due to extravasation of mucin from the tumour into the stroma.
Reactive hemophagocytic syndrome is a clinico-pathologic entity characterized by systemic proliferation of non-neoplastic histiocytes showing phagocytosis of hemopoietic cells, resulting in blood cytopenia. It is best known to be associated with virus infection, but other associated diseases have also been implicated. The clinical and pathological findings of 7 fatal cases are described. The syndrome affected both sexes of a wide age range, and all patients had fever. Significant laboratory findings were blood cytopenia, abrupt drop in the blood cell counts, deranged liver function tests and abnormal coagulation profile. The associated diseases were diverse: two patients had bacterial infection; two had peripheral T-cell lymphoma; one had disseminated undifferentiated carcinoma of the ovary; one had both tuberculosis and disseminated nasopharyngeal carcinoma, and one had no obvious underlying disease. It is postulated that lymphokines secreted by lymphoid cells or tumor cells may be responsible for the systemic activation of histiocytes. The differential diagnosis from malignant histiocytosis is discussed.
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Sclerosing adenosis is a common proliferative lesion of the mammary lobule which is not associated with an increased risk of developing breast cancer. An unusual case of florid sclerosing adenosis showing extensive cancerization by intraductal carcinoma is reported. The neoplastic nature of the sclerosing lesion can be recognized by the unusual distension of the tubules by cells and the subtle cytological changes, and further confirmed by finding foci of classical intraductal carcinoma.
The clinical features of thirteen Chinese patients with lupus anticoagulant were described. They were noted to conform to those reported among Caucasians and tend to suggest that the term 'lupus anticoagulant' is a double misnomer.
A patient with immunohistochemically confirmed nasal T-cell lymphoma is reported. He developed systemic histiocytosis with marked hemophagocytosis, simulating malignant histiocytosis. The differential diagnosis from the latter is discussed.
A 13-year-old boy presented with progressive bilateral lower limb weakness due to exradural granulocytic sarcoma of the spine. After surgical decompression and radiotherapy, he remained in complete remission 6 years after initial diagnosis. The possible reasons for the favorable outcome of this unique case are discussed.
An extraskeletal chondroma occurring over the dorsum of the wrist of a 61-year-old woman is reported. The lobulated tumor is cellular and shows mild-to-moderate nuclear pleomorphism of the chondroid cells. A unique feature is that some tumor cells are univacuolated and multivacuolated owing to accumulation of lipid, mimicking the appearances of lipoblasts.
Eight cases of malignant lymphoepithelial lesion (MLEL) of major salivary glands, seven of which occurred in Southern Chinese patients, are reported. All but two of the patients were older than 40 years of age; there were five male and three female patients. The parotid and submandibular glands were the sites of origin in equal numbers of cases. Six patients had elevated titers of serum IgA against Epstein-Barr virus capsid antigen. Seven remained well after surgery and local radiation therapy, and one died of miliary tuberculosis without evidence of residual neoplasm. Histologically, MLELs were characterized by syncytial clumps of large cells with vesicular nuclei and prominent nucleoli, admixed with abundant small lymphocytes and plasma cells. Two features not emphasized previously in the literature were the presence of reactive histiocytes in some epithelial islands, producing a starry sky pattern, and perineural invasion, which was identified in four cases. The tumor cells showed strong immunostaining for cytokeratin. The literature concerning this rare tumor is reviewed, and the differential diagnosis between MLEL and benign lymphoepithelial lesion, metastatic undifferentiated carcinoma, and malignant lymphoma is discussed.
Passive transfer of frambesial immune serum is capable of conferring complete protection on hamsters against challenge with Treponema pallidum ssp. pertenue. Treponemicidal activity in the pooled immune serum is relatively high. Immune serum and its immunoglobulin fractions, especially IgG2, also killed T. pallidum ssp. pertenue in vitro. Treponemicidal activity was present only when immune serum was administered to hamsters within a short time (three days) of frambesial challenge. By contrast, administration of pooled immune serum to hamsters infected for more than one week failed to reduce the number and size of lesions and the weight and number of treponemes in the lymph nodes. These results suggest that hamsters can develop the humoral components necessary to protect them against frambesial challenge, but these components are unable to destroy treponemes at the primary foci of infection.
The optically clear nucleus has been recognized widely as an important histological feature of papillary carcinoma of the thyroid, and it is now considered by many workers as standing on an equal basis with the papillae for the diagnosis of this tumor. However, clear nuclei are sometimes patchy in distribution or absent in papillary carcinoma, and may be difficult to differentiate from pseudoclear nuclei which may be found in a variety of thyroid lesions. This study was undertaken to determine whether the grooving of the nuclei, a well-recognized electron-microscopic feature, can serve as an additional reliable light microscopic diagnostic criterion of papillary carcinoma. The histological sections of 103 consecutive cases of thyroid carcinoma, (including 89 cases of papillary carcinoma), 100 consecutive noncancer thyroidectomy specimens, and five cases of Hashimoto's thyroiditis were reviewed. Grooved nuclei were found in all cases of papillary carcinoma in almost every high-power microscopic field, and in the two cases of poorly differentiated thyroid carcinoma. Similar nuclei were found in only a very occasional field in four cases of adenoma, and one case each of multinodular goiter and Hashimoto's thyroiditis. We conclude that the deep grooving of the nuclei is a useful cytological feature for the diagnosis of papillary thyroid carcinoma.
Three cases of dermal nerve sheath myxoma have been studied by light microscopy, histochemistry and immunohistochemistry. The pertinent literature has been reviewed. This lesion, which is a rare benign tumour of probable nerve sheath origin, arises most often in young adults and shows a predeliction for females. Histologically it has a characteristic appearance. Histochemically, the heteroglycan content of the mucoid matrix is more in keeping with a cartilaginous lesion. The histogenesis and differential diagnosis are discussed.
Four cases of multilobated B-cell lymphoma, one follicular and three diffuse, are described. Many of the lymphoma cells show marked lobulation of the nuclei, and possess multiple prominent nucleoli. There are admixed classical centrocytes, classical centroblasts, and cells with morphology intermediate between classical centroblasts and multilobated cells. Multilobated cells are also observed in small numbers in germinal centres of lymph nodes showing reactive follicular hyperplasia. We believe that the multilobated B-cell may represent one form of centroblast during transition between the centroblastic and centrocytic stages. Multilobated B-cell lymphoma may be its neoplastic counterpart in which the nuclear lobulation is further exaggerated.
We have developed a sensitive, solid phase radioimmunoassay (RIA) to quantify the amount of complement (C') fixation by anti-double-stranded DNA (anti-dsDNA) antibodies and have studied sera from 48 patients with systemic lupus erythematosus (SLE). 46% of the patients were positive in this assay. There was no correlation with serum C' levels, and only weak correlation with anti-dsDNA activity as measured by a solid phase RIA. An association was shown between positive values for C' fixation by anti-dsDNA antibodies and the presence of active lupus (p less than 0.01); there was a similar association with the presence of active renal disease in those patients with raised DNA binding (p less than 0.01). Our results suggest that quantitative measurement of C' fixation by anti-dsDNA antibodies may provide information about the pathogenicity of such antibodies in patients with SLE and be a better guide to potential end organ damage than the conventional measurement of DNA binding.
The cell surface markers of 75 cases of non-Hodgkin's lymphoma were studied on cryostat sections using a panel of monoclonal antibodies. Forty-nine cases (65.3%) were found to express a B-cell phenotype, 23 cases (30.7%) a T-cell phenotype, 1 case (1.3%) a histiocytic phenotype and 2 cases (2.7%) no demonstrable surface markers. Follicular lymphoma accounted for only 10.7% of the cases. Most B-cell lymphomas expressed IgM-lambda or IgM-IgD-lambda, but a few failed to express surface immunoglobulin. Among the 23 cases of T-cell lymphoma, 22 were of peripheral T-cell type; most were of helper-cell (T4) phenotype and a significant number expressed J5 (CALLA) and I2 (HLA-DR). The present study shows that the percentage of T-cell lymphoma in Chinese is higher than in Caucasians, but lower than in Japanese. However, when the age-adjusted incidence of non-Hodgkin's lymphoma is considered, the incidence rates of T-cell lymphoma in Hong Kong Chinese and Japanese in areas non-endemic for adult T-cell lymphoma/leukemia are similar; the incidence in Americans is similar or slightly lower. The major difference between the races is that B-cell lymphoma, particularly the follicular type, is much rarer in Asians than Americans.
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The clinicopathological features of histiocytic necrotizing lymphadenitis in 9 patients are described. This disease occurs predominantly in the second and third decades of life, and in our series, is slightly more common in males. The commonest presentation is lymph node enlargement. Fever is also common, and was the mode of presentation in two patients. Laboratory investigations are non-contributory, with only an occasional case showing leucopenia or a raised erythrocyte sedimentation rate. The disease is self-limiting in all patients. The characteristic histological feature is the presence of pale nodules in the paracortex, consisting of a mixture of activated lymphoid cells, histiocytes and karyorrhectic debris. Granulocytes are strikingly absent.
To determine the predictive value of the IgG anticardiolipin antibody (ACA) test for thrombosis, recurrent fetal loss, and thrombocytopenia, the clinical features of 121 patients with varying antibody levels were studied. When patients were grouped into high-positive, low-positive, and normal groups according to their ACA levels, there were strong statistical correlations with arterial thrombosis, venous thrombosis, fetal loss, thrombocytopenia, and a positive Coombs' test. At levels of 7 SD and above, the test was highly specific (greater than 80%) and predictive (greater than 70%) for thrombosis, thrombocytopenia, and recurrent fetal loss. This study suggests that the IgG ACA test may be a useful predictor for thrombosis, recurrent fetal loss, and thrombocytopenia in patients with autoimmune disorders.