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Biomedical subjects

J K Chan

Publications and source records attributed to J K Chan.

At least 163 records · Page 9Linked to original sources
PubMed1995

Low frequency association of the t(2;5)(p23;q35) chromosomal translocation with CD30+ lymphomas from American and Asian patients. A reverse transcriptase-polymerase chain reaction study.

Although cytogenetic data suggest that the t(2;5)-(p23;q35) translocation occurs in many cases of CD30+ lymphomas, the exact frequency of this event is still unknown. To clarify this issue and its epidemiological characteristics, we examined 37 formalin-fixed, paraffin-embedded specimens of CD30+ lymphomas from the United States and Hong Kong by reverse transcriptase-polymerase chain reaction (RT-PCR) for the status of the NPM and ALK genes, which are typically juxtaposed by the t(2;5) translocation. Thirty-four cases were classified as anaplastic large cell lymphomas (ALCL), 2 cases as non-anaplastic large cell lymphomas (LCL), and 1 case as the small cell variant of CD30+ lymphoma. The t(2;5) translocation was detected in 6 cases (16%), including 3 of 18 American patients and 3 of 19 cases from Hong Kong. All cases had a 185-bp NPM RT-PCR product as detected by Southern blot analysis, indicating adequate preservation of mRNA. The 6 positive cases were among 4 of 34 adult lymphomas, as compared with 2 of 3 childhood cases. Five of 17 T-lineage cases were t(2;5)-positive, compared with 1 of 15 B-lineage cases and none of the 5 null-cell or mixed lineage cases. Our results therefore show that t(2;5) occurs at a low frequency among CD30+ lymphomas, at least in our adult-dominated series.

Adolescent↗
PubMed1994

The spectrum of chronic lymphoproliferative disorders in Chinese people. An analysis of 64 cases.

BACKGROUND: Chronic lymphoproliferative disorders are considered rare in Oriental patients and are thought to constitute only 2% of all leukemias in these patients, compared to 20-30% in Western patients. We conducted a retrospective analysis of Chinese patients with chronic lymphoproliferative disorders to define the frequency and spectrum of these disorders. METHODS: A consecutive series of Chinese patients with leukemia and lymphoproliferative disorders seen at two regional hospitals in Hong Kong were analyzed retrospectively. The diagnosis of chronic lymphoproliferative disorders was based on morphologic and immunologic criteria proposed by the French-American-British Cooperative Study Group. RESULTS: Sixty-four Chinese patients with chronic lymphoproliferative disorders were identified, and these patients constituted 19% of a total of 342 cases of leukemia diagnosed in 3 years. Chronic lymphocytic leukemia was the most common form, occurring at a frequency of 12.5% of all leukemias. The clinicopathologic features of these patients were similar to those of Western patients, except that Chinese patients tended to present with more advanced (Rai's Stages III and IV; Binet's Stage C) and bulky (splenomegaly > 9 cm) disease, and expressed lambda light chain about six times more frequently. Other chronic lymphoproliferative disorders identified in this study included prolymphocytic leukemia, mantle zone lymphoma, hairy cell leukemia, splenic lymphoma with villous lymphocytes, large granular lymphocyte leukemia, and Sezary syndrome. The authors did not identify any case of human T-cell lymphotropic virus-I-related lymphoproliferative disorders within the study period. CONCLUSION: In addition to providing the frequencies of various chronic lymphoproliferative disorders in southern Chinese people, this study also showed that these disorders no longer should be considered rare in this population. Inherent biologic differences between lymphoproliferative disorders in Chinese and Western patients also may exist.

Adult↗
PubMed1994

Experience with the management of ovarian germ cell tumors in Chinese patients.

Treatment results of 37 consecutive patients with primary ovarian germ cell tumors (OGCTs) were analyzed. Thirty-three were referred after initial laparotomy and four were first seen at relapse. Four patients with stage I dysgerminoma and grade 1 immature teratoma were observed after operation without recurrence. There was also no relapse in eight patients with dysgerminoma given postoperative irradiation (whole abdomen, median 30 Gy). Twenty-five patients (3 dysgerminomas, 11 immature teratomas, 9 endodermal sinus tumors, and 2 mixed germ cell tumors) received short-term cis-platinum-based chemotherapy. Six out of eight measurable tumors treated by chemotherapy had complete remission. Complete follow-up information was obtained in 35 out of 37 patients. The 4-year actuarial survival rates of the whole group and those referred immediately after initial surgery were 94.1 and 100%, respectively. cis-Platinum was substituted by carboplatin in eight cases but this did not affect treatment result. Nonetheless, deaths occurred in two of four patients referred at relapse with extensive disease and initially treated with suboptimal regimens. Chemotherapy-induced side effects were common but mostly tolerable and were related to cis-platinum and bleomycin. The results of this series show that cis-platinum-based chemotherapy is so effective that nearly 100% cure can be achieved in OGCTs and suggest that it is important to institute optimal chemotherapy from the start. On the other hand, common side effects of treatment and possible late toxicities make it desirable for future studies to see whether chemotherapy intensity could be reduced in patients with good prognosis.

Adolescent↗
PubMed1994

In situ localization of Epstein-Barr virus encoded RNA in non-nasal/nasopharyngeal CD56-positive and CD56-negative T-cell lymphomas.

We recently reported a group of non-nasal/nasopharyngeal hematolymphoid malignancies expressing the natural killer cell marker CD56, characterized by frequent extranodal localization, angiocentricity, and aggressive clinical course (HUM PATHOL 23:798-804, 1992). Because we have shown a very strong association of Epstein-Barr virus (EBV) with CD56-positive T-cell lymphomas of the nose nasopharynx, we asked whether a similar association also occurs with the non-nasal CD56-positive T-cell lymphomas. In situ localization of EBV encoded RNA (EBER) was performed on paraffin sections of 15 such cases, including the nine previously reported cases and six new cases (three showing prominent hepatosplenic involvement and three showing involvement of one or more extranodal sites, such as the parotid gland, tonsils, gastrointestinal tract, skeletal muscle, and testis). A case was considered positive when the majority of the tumor cells showed nuclear signal. Ten cases showed EBER positivity, and all but one of them were negative for CD3 and other T-cell markers, except CD2. Only one of four cases showing a CD3-positive phenotype was EBER positive. Of the remaining two CD3-negative EBER-negative cases, one showed a histiocytic phenotype and the other was positive for multiple T-cell markers. Among 15 cases of CD56-negative non-nasal peripheral T-cell lymphoma studied for comparison, six were CD3-negative, among which three showed EBER positivity. All nine CD3-positive cases were EBER negative. Five cases (three CD3 positive and two CD3 negative) showed rare isolated (< 1%) EBER-positive tumor cells. We conclude that among non-nasal T-cell lymphomas, EBV is strongly correlated with CD56 positivity (66.7% v 20%), and the positive cases almost always show an immunophenotype identical to that commonly observed in nasal lymphomas (CD2 positive, CD3 negative, and CD56 positive). Thus, EBV may play an etiologic role in these CD56-positive lymphomas. There is also a correlation between EBER positivity and CD3 negativity, irrespective of the CD56 status. The presence of isolated EBER-positive cells in CD56-negative T-cell lymphomas, occurring at a frequency similar to that reported in the European population, probably represents secondary infection of tumor cells.

Adult↗
PubMed1994

Fine-needle aspiration cytologic diagnosis of Kikuchi's lymphadenitis. A report of 27 cases.

Kikuchi's lymphadenitis is a self-limiting condition typically affecting young patients. Surgical biopsy is unnecessary if a firm diagnosis can be rendered by fine-needle aspiration cytology (FNAC). The authors report the FNAC findings for 27 cases, including 24 female and 3 male patients aged 12 to 43 years. Histologic sections of FNAC cell blocks and excisional biopsy specimens were available in 26 and 9 cases, respectively, for confirmation of the diagnosis. In the smears, karyorrhectic and granular debris were mixed with two distinctive cell types: (1) phagocytic histiocytes with peripherally placed "crescentic" (sometimes elongated or twisted) nuclei and abundant cytoplasm containing phagocytosed karyorrhectic or eosinophilic granular debris, easily distinguishable from tangible-body macrophages, which possessed central round nuclei, and (2) medium-sized cells possessing eccentrically placed round nuclei, fairly condensed chromatin, and a moderate amount of amphophilic cytoplasm, consistent with plasmacytoid monocytes. Also present were nonphagocytic histiocytes with twisted nuclei and delicate chromatin and immunoblasts that sometimes showed atypical features such as irregular foldings of the nuclei. Neutrophils were sparse or absent. Review of the FNAC findings of 50 lymph nodes involved by various reactive processes, tuberculosis, and lymphoma for comparison showed that although tangible-body macrophages and debris were not uncommon, very few phagocytic histiocytes with crescentic nuclei were observed, in only 2 cases; plasmacytoid monocytes were observed in 4 cases. The constellation of features described above permits diagnosis of Kikuchi's lymphadenitis by FNAC. Because of morphologic similarities between lupus lymphadenitis and Kikuchi's lymphadenitis, however, serologic studies are warranted to exclude systemic lupus erythematosus.

Adolescent↗
PubMed1994

Primary cutaneous plasmacytoma--report of two cases and review of the literature.

Primary cutaneous plasmacytomas are very rare. In this report, we describe two such cases and review the literature on this entity. Both patients presented with a slowly growing, painless, and solitary mass on the chest wall. Histologically, one case was composed of mature-looking plasma cells, while the other was composed of immature and anaplastic plasma cells, infiltrating the dermis. The epidermis was spared. Kappa light-chain restriction was demonstrated by immunohistochemical techniques in both cases. There was no evidence of marrow disease even on repeated marrow biopsies, although extracutaneous lesions were detected in one patient. One remained in complete remission 6 years following local irradiation. The other patient was treated with local irradiation and systemic chemotherapy, with a complete response, but this was followed by multiple cutaneous recurrences and further remissions by treatment with cytotoxic agents. The present cases and those reported in the literature illustrate well the variable clinical course of primary cutaneous plasmacytoma. Although cure can apparently be achieved in some patients by local radiation therapy, more than half of the cases relapse or progress to myelomatosis. The disease-related mortality is at least 40%. Thus cutaneous plasmacytoma appears to be more aggressive than noncutaneous extramedullary plasmacytomas and should be separately categorized from them in future studies.

Aged↗
PubMed1994

Follicular dendritic cell tumors of the oral cavity.

Follicular dendritic cell tumors are uncommon, and all the reported cases have occurred as primary lymph node tumors. We report two cases in the oral cavity, one in the soft palate and one in the tonsil. The tumors were characterized by sheets, whorls, and storiform arrays of spindly and syncytial-appearing cells with oval nuclei, fine chromatin, distinct nucleoli, and occasional nuclear pseudoinclusions. Multinucleated forms were present and were prominent in one case. An unusual feature was the presence of irregular pseudovascular spaces, which could raise a concern for vascular neoplasm. Because the tumors showed cohesive growth and a sharp interface with the fibrous stroma, they could also be mistaken for carcinoma, sarcoma, or melanoma. After radiation therapy, the palatal tumor showed a greater degree of nuclear pleomorphism, numerous nuclear pseudoinclusions, and striking nuclear grooving and foldings, mimicking interdigitating reticulum cell tumors. The diagnosis in both cases was confirmed by immunoreactivity with CD21 and CD35 and by ultrastructural demonstration of interdigitating cell processes with desmosomes. Both tumors also showed unexpected immunoreactivity with muscle-specific actin. Follicular dendritic cell tumor merits wider recognition of its possible extranodal occurrence as well as its full morphological spectrum in order to better define its behavior.

Adult↗
PubMed1994

Detection of Epstein-Barr viral RNA in sinonasal undifferentiated carcinoma from Western and Asian patients.

Undifferentiated carcinoma of the nasopharynx has a well-known association with Epstein-Barr virus (EBV), but only an inconsistent relationship has been identified in undifferentiated carcinomas occurring at other sites. We investigated 22 formalin-fixed, paraffin-embedded cases of sinonasal undifferentiated carcinomas (SNUCs) occurring in Western and Asian patients. A highly sensitive in situ hybridization method was performed using an antisense oligonucleotide probe to the EBER1 gene of EBV. We identified EBV RNA in seven of 11 SNUCs from Asian patients, but in none of the Western SNUC patients (0/11). The EBER1 signal was present in all or virtually all of the tumor cell nuclei in the seven EBV-RNA-positive Asian SNUCs. The latent membrane protein-1 (LMP1) of EBV was not identified in any of the five positive cases tested. Our results suggest that genetic predisposition or environmental/geographical cofactors play an important role in determining the strength of the association of SNUC with EBV.

Adult↗
PubMed1994

Nodular desmoplastic variant of trichoblastoma.

A case of an unusual, previously unreported, nodular desmoplastic variant of trichoblastoma (hair germ neoplasm) in the scalp of a 65-year-old woman is reported. Four discrete nodules were present in close proximity at presentation. Another nodule developed in the same vicinity 3 1/2 years after excision, and there was no further recurrence 2 1/2 years later. The tumors were located in the dermis, made up of cords of primitive hair germ-like structures radiating down from discrete hyalinized nodules located in the superficial dermis. There were small foci of keratinization or mucoid change within the epithelial islands. Toward the deep portion of the tumor, the epithelial cells became spindly and grew in a more dispersed pattern, within a desmoplastic stroma. There was also infiltration of the epineurium of the cutaneous nerves and arector pili muscle. This uncommon benign neoplasm of hair germ merits wider recognition; in particular, this desmoplastic variant may mimic invasive carcinoma, morphea-type basal cell carcinoma, desmoplastic trichoepithelioma, and desmoplastic trichilemmoma. Distinguishing this variant from the former two possibilities is particularly important in order to avoid unduly aggressive treatment.

Aged↗
PubMed1994

Follicular dendritic cell tumor and vascular neoplasm complicating hyaline-vascular Castleman's disease.

The localized form of hyaline-vascular Castleman's disease may rarely be complicated by a vascular neoplasm, which appears to arise in a background of vascular hyperplasia. We report a case complicated by follicular dendritic cell tumor, a hitherto undescribed occurrence that is expected from the presence of a "dysplastic" component of follicular dendritic cells in Castleman's disease. The patient had a large tumor mass in the mesocolon, associated with multiple small peritoneal deposits. The lesion showed typical histologic features of follicular dendritic cell tumor with storiform arrangement of spindly cells and admixture of small lymphocytes. The follicular dendritic cell nature of the tumor was confirmed by immunoreactivity with CD21 and CD35 antibodies and by ultrastructural demonstration of cell processes connected by desmosomes. Hyaline-vascular follicles were identified at the peripheral portion or occasionally scattered in the center of the tumor. Rarely, follicle-like structures were formed by tumor cells, possibly representing in situ malignant change. In addition, there was a small focus of vascular neoplasm comprising well-formed pericyte-rich small blood vessels devoid of cellular atypia. This report of the development of follicular dendritic cell tumor in Castleman's disease therefore completes the picture in that tumors corresponding to each cell type that proliferates in Castleman's disease have now been documented.

Adult↗
PubMed1994

Detection of Epstein-Barr viral RNA in malignant lymphomas of the upper aerodigestive tract.

Recent studies have suggested a probable etiologic association between Epstein-Barr virus (EBV) and nasal lymphomas, irrespective of geographic location. This study was performed to investigate the strength of association of EBV with non-Hodgkin's lymphomas of the upper aerodigestive tract, based on a large series of cases that have been thoroughly immunophenotyped on frozen tissues. A sensitive in situ hybridization technique was used to detect EBV encoded RNA (EBER) in paraffin sections. Among 30 cases of nasal/nasopharyngeal T-cell lymphoma, 25 (83.3%) were EBER-positive. In the positive cases, most of the neoplastic cells showed strong nuclear signals. Further analysis of this group of tumors showed that all 21 cases (100%) with a CD56+ CD3-phenotype were EBER positive, whereas four of nine cases (44.4%) with a CD56-negative immunophenotype were positive. Only one of 10 cases (10%) of nasal/nasopharyngeal B-cell lymphoma was EBER positive; the positive case was a diffuse mixed-cell lymphoma and could not be distinguished morphologically from the negative cases. Among the 21 cases of lymphoma of the tonsils and back of the tongue (20 B-lineage and one T-lineage), none was EBER positive. In the normal mucosa of the nose/nasopharynx or tonsil (20 cases studied), only very rare EBER-positive small lymphocytes were found in two cases. The almost exclusive detection of EBER in nasal/nasopharyngeal T-cell neoplasms among the lymphomas of the upper aerodigestive tract suggests that EBV probably plays an etiologic role in the pathogenesis of this group of tumors and is not simply a passenger virus, and neither is this merely a site-dependent phenomenon in view of the weak association with nasal/nasopharyngeal B-cell lymphoma.

Herpesvirus 4, Human↗
PubMed1994

Histologic changes in the breast after fine-needle aspiration.

Fine-needle aspiration biopsy (FNAB) of the breast has been widely used in many centers worldwide for the initial management of patients with breast lumps. However, little has been written on the morphologic changes secondary to this commonly applied procedure. Thus we performed a retrospective study on 184 consecutive breast-excision specimens with a history of FNAB. Seventeen cases (9.2%) showed changes definitely attributable to the FNAB procedure, including three cases of near total destruction of the lesion as a result of hemorrhage (one case) or infarction (two cases), focal hemosiderin deposition (seven cases), hemorrhage with organization at the periphery (six cases), and a case of ductal papilloma showing a previously undescribed occurrence of benign epithelial implantation. The latter exhibited alarming histologic features simulating invasive carcinoma by virtue of the presence of small narrow tubules with mild cellular atypia haphazardly distributed in the fibrogranulation tissue around the papilloma; the tubules were confirmed to be benign by the presence of muscle-specific actin-positive myoepithelial cells. Other changes were possibly attributable to the FNAB procedure, including linear necrosis in the peripheral portion of the tumor (six cases), intraluminal hemorrhage in fibroadenoma (five cases), and multicentric hemorrhage in the mucinous carcinomas (four cases). We conclude that the rare occurrence of extensive tissue necrosis after FNAB can pose great difficulties in definitive diagnosis of the lesion in the subsequent excision specimen. Other changes are relatively minor, but the occurrence of benign implantation after FNAB may lead to an erroneous diagnosis of invasive carcinoma.

Biopsy, Needle↗