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J K Chan

Publications and source records attributed to J K Chan.

At least 37 records · Page 2Linked to original sources
PubMed2001

Anaplastic lymphoma kinase expression in inflammatory pseudotumors.

Anaplastic lymphoma kinase (ALK), a hallmark of anaplastic large cell lymphoma, has recently been implicated in the genesis of some inflammatory pseudotumors (inflammatory myofibroblastic tumors) in children and young adults. The aim of this study was to determine the frequency of its expression among inflammatory pseudotumors, and to characterize the clinicopathologic features of the positive cases. Sixty-one cases of inflammatory pseudotumors were retrieved from the surgical pathology archives and consultation files. Paraffin sections were immunostained with the antibody ALK1. The patients ranged in age from 0.5 to 79 years (median age, 50 years), with 10 patients (16.4%) younger than 20 years. Five cases (8.2%) were ALK+, including two of six urogenital inflammatory myofibroblastic tumors, none of eight pulmonary inflammatory pseudotumors, three (one adrenal, one small bowel, one liver) of 31 extrapulmonary inflammatory pseudotumors, none of nine hepatic/splenic inflammatory pseudotumors expressing follicular dendritic cell markers and harboring Epstein-Barr virus, and none of seven inflammatory pseudotumors of the lymph node. When only those patients 40 years or younger were considered, the ALK positivity rate became 21.7% (five of 23). All five ALK+ cases occurred in young patients aged 0.5 to 37 years, who were alive and well at 3.5 to 17 years. The tumors exhibited a spectrum of histologic features typical of inflammatory pseudotumors/myofibroblastic tumors, but there was at least focal nuclear atypia. Immunostaining for ALK produced fibrillary or granular cytoplasmic staining in the neoplastic cells, sometimes with cell membrane accentuation. This study confirms that ALK is implicated in a proportion of inflammatory pseudotumors, and is generally associated with a favorable outcome. The results also support the heterogeneity of inflammatory pseudotumors, with the follicular dendritic cell/Epstein-Barr virus-positive cases and those occurring in lymph nodes representing different biologic entities.

Adolescent↗
PubMed2001

Primary histiocytic lymphoma of the central nervous system: a neoplasm frequently overshadowed by a prominent inflammatory component.

True histiocytic lymphoma, as defined by strict criteria, is a very rare neoplasm. We describe three cases occurring as primary tumors in the central nervous system. The patients, two females and one male, ranged in age from 11 to 69 years. The tumors involved the brain in two cases and spinal cord in one, with a size ranging from 7 to 17 mm. Two patients died at 4 months and 8 months, respectively, and one was alive with disease at 5 months. Pathologically, the tumors comprised groups and sheets of noncohesive large cells with pleomorphic vesicular nuclei, distinct nucleoli, and abundant eosinophilic cytoplasm. A dense inflammatory infiltrate consisting of neutrophils, lymphocytes, plasma cells, and histiocytes was present, with multiple foci of necrosis and abscess formation. All three cases demonstrated an identical immunophenotype: positive for CD68 and lysozyme; focally positive for S-100 protein, CD45RB, and CD4; and negative for CD3, CD20, CD21/CD35, CD1a, CD30, ALK1, myeloperoxidase, glial fibrillary acidic protein, and cytokeratin. The proliferative index ranged from 20% to 35%. Ultrastructural examination further confirmed the histiocytic nature of the tumor cells, characterized by irregularly folded or multisegmented nuclei and abundant cytoplasm containing lysosomes; Birbeck granules, interdigitating cell processes, and cell junctions were not found. Although the presence of abundant inflammatory cells could obscure the neoplastic histiocytes, making the distinction from inflammatory conditions difficult, awareness of this unusual histologic feature and the invariable finding of pleomorphic cells in some areas of the lesion permit the correct diagnosis to be made.

Adult↗
PubMed2001

Bone marrow involvement by nasal NK cell lymphoma at diagnosis is uncommon.

To look for subtle evidence of marrow involvement in nasal NK cell lymphoma at diagnosis, we retrospectively studied trephine biopsy specimens from 25 consecutive patients by 2 sensitive techniques: CD56 immunohistochemistry and Epstein-Barr virus-encoded RNA in situ hybridization (EBER ISH). Only 2 patients had marrow involvement by NK cell lymphoma at diagnosis. In 3 additional patients, marrow involvement developed during or after systemic recurrence. All 5 positive cases were revealed by EBER ISH, but only 3 cases showed CD56 immunoreactivity. Among the 5 cases, only 2 were recognized by morphologic assessment. All 5 patients died, often within a short period, compared with a mortality of 50% for patients without demonstrable marrow involvement. Marrow involvement is distinctly uncommon in nasal NK cell lymphoma at diagnosis, and EBER ISH is the most sensitive technique for the demonstration of occult NK cell lymphoma. Despite the low frequency of marrow involvement in nasal NK cell lymphoma, EBER ISH is worthwhile to identify the minor subgroup of patients with a high likelihood of early death due to disease and when autologous bone marrow or peripheral blood stem cell transplantation is contemplated.

Adult↗
PubMed2001

Determinants of continuous positive airway pressure compliance in a group of Chinese patients with obstructive sleep apnea.

OBJECTIVE: To assess continuous positive airway pressure (CPAP) compliance and factors associated with CPAP compliance among Chinese patients with obstructive sleep apnea (OSA). DESIGN: A prospective study of 112 consecutive patients with newly diagnosed OSA commencing CPAP treatment. SETTING: A university teaching hospital. MEASUREMENTS AND RESULTS: The following factors were evaluated for any correlation with objective CPAP compliance (effective mask pressure [hours per day]) at 1 month and 3 months: age, baseline apnea-hypopnea index (AHI), common OSA symptoms, minimum arterial oxygen saturation (SaO(2)), mean SaO(2), arousal index (AI), Epworth sleepiness scale (ESS), education level, CPAP levels, satisfaction with CPAP, side effects, and machine cost. There were 101 male and 11 female patients, with a mean (+/- SD) age of 45.6 +/- 1.2 years; body mass index, 29.3 +/- 5.2 kg/m(2); AI, 60 +/- 18/h; AHI, 48 +/- 24/h; minimum SaO(2) of 70 +/- 17%; and mean SaO(2) of 86 +/- 7%. ESS fell from 12.9 +/- 4.0 (baseline) to 5.2 +/- 4.7 at 3 months (p < 0.001). Objective CPAP compliance was 5.4 +/- 1.6 h/d and 5.3 +/- 1.6 h/d, while 75% and 72% of our patients were using CPAP objectively for > or = 4 h/d and at least 70% of the nights per week at 1 month and 3 months, respectively. Following univariate analysis of variance, a high baseline AHI (p = 0.006 and p = 0.004) was associated with higher objective CPAP compliance at 1 month and 3 months, respectively. CONCLUSION: CPAP usage and compliance were high in this patient population. A high baseline AHI was the only significant independent predictor of better CPAP compliance.

Age Factors↗
PubMed2001

Immunostaining for thyroid transcription factor 1 and cytokeratin 20 aids the distinction of small cell carcinoma from Merkel cell carcinoma, but not pulmonary from extrapulmonary small cell carcinomas.

OBJECTIVE: To study the expression of thyroid transcription factor 1 (TTF-1) and cytokeratin 20 (CK20) in pulmonary small cell carcinomas, extrapulmonary small cell carcinomas, and Merkel cell carcinomas, and thereby determine whether these markers are helpful in distinguishing these 3 groups of small cell neuroendocrine carcinomas. MATERIALS AND METHODS: Immunostaining for TTF-1 and CK20 was performed in 102 cases of small cell carcinoma (pulmonary, 52; extrapulmonary, 50) and 23 cases of Merkel cell carcinoma. The results for the 3 groups were compared. RESULTS: Thyroid transcription factor 1 was expressed in 82.7% of pulmonary small cell carcinomas, 42.0% of extrapulmonary small cell carcinomas (range, 33.3--53.3% for the various sites), and 0% of Merkel cell carcinomas. Cytokeratin 20 staining was consistently negative in pulmonary small cell carcinomas, and positive in 4.0% of extrapulmonary small cell carcinomas and 100% of Merkel cell carcinomas. CONCLUSIONS: Immunostaining for TTF-1, especially when combined with immunostaining for CK20, can aid in the distinction between Merkel cell carcinoma and small cell carcinoma (both pulmonary and extrapulmonary). However, in individual cases, these markers cannot be used to distinguish between pulmonary and extrapulmonary small cell carcinomas due to the extensive overlap in immunophenotypes.

Carcinoma, Merkel Cell↗
PubMed2001

Clear cell variant of fibrolamellar carcinoma of the liver.

Fibrolamellar carcinoma of the liver is a distinctive variant of hepatocellular carcinoma characterized histologically by trabeculae of oncocytic cells with intervening lamellae of collagen fibers. We describe a case with a prominent component of clear cells, a feature not previously recognized in this tumor type. The patient was a 59-year-old woman incidentally found to have a solitary liver tumor, measuring 5 cm. Pathologic examination revealed a circumscribed, firm, tan tumor with peculiar concentric streaks. Oncocytic cells and clear cells were arranged in trabeculae separated by lamellae of collagen or sinusoids. The clear cells possessed abundant finely reticulated clear cytoplasm, which was highlighted by trichrome stain and immunostaining with antimitochondria antibody. Ultrastructurally, the cytoplasm of the clear cells was packed with empty membrane-bound vesicles that occasionally contained short cristae. The features suggested that the clear cell change resulted from ballooning and rarefactive changes of mitochondria. Clear cell fibrolamellar carcinoma should not be confused with conventional clear cell hepatocellular carcinoma, since the former is associated with a more favorable prognosis.

Carcinoma, Hepatocellular↗
PubMed2001

Vaginal hysterectomy as primary treatment of endometrial cancer in medically compromised women.

OBJECTIVE: To study the survival, rates and patterns of recurrence, and perioperative morbidity in medically compromised women with endometrial cancer treated by primary vaginal hysterectomy. METHODS: Fifty-one patients with endometrial cancer treated initially by vaginal hysterectomy between 1977 and 1999 were identified at the University of California, Irvine Medical Center and affiliated hospitals. Data were retrieved from hospital and office records. Statistical analysis, including Kaplan-Meier methods, was performed and the disease-specific survival rates were estimated. This study has 80% power to demonstrate a greater than 20% improvement in 5-year survival over historical controls. RESULTS: Fifty-one women with uterine carcinoma clinically confined to the uterus underwent primary vaginal hysterectomy with (n = 26) or without (n = 25) salpingo-oophorectomy. Eighty-four percent were obese with a body mass index greater than 27. Additional risk factors for surgical complications included hypertension (57%), diabetes mellitus (27%), and cardiovascular disease (18%). One-third of patients had three or more risk factors. Surgical morbidity included one episode of acute hemorrhage necessitating transfusion and abdominal exploration. Blood transfusions were given to four additional patients. There were no perioperative deaths. Five women recurred and expired at a median of 13 months (range 3--53 months) after surgery. The 3- and 5-year disease-specific survival rates were 91.4% and 88.0%, respectively. CONCLUSION: Vaginal hysterectomy for the initial treatment of early-stage endometrial cancer is associated with a high rate of cure and minimal morbidity. Thus, it may be considered a reasonable alternative to the abdominal approach in medically compromised women.

Adult↗
PubMed2000

Follicular dendritic cell sarcoma of the neck: report of two cases complicated by pulmonary metastases.

BACKGROUND: Follicular dendritic cell (FDC) sarcoma is an uncommon neoplasm occurring primarily in lymph nodes but also in extranodal sites. A correct diagnosis can be difficult to make, especially in the latter sites. METHODS: Two patients with FDC sarcoma of the cervical soft tissues that metastasized to the lungs are reported. Both were initially misdiagnosed as having CASTLE (carcinoma showing a thymus-like element). Additional immunohistochemical stains were performed. RESULTS: The primary tumors showed jigsaw puzzle-like lobulation resembling thymic epithelial tumor and consisted of spindly cells arranged in fascicles, whorls, and a storiform pattern. The spindly cells had indistinct cell borders, vesicular nuclei, and distinct nucleoli. Perivascular spaces were present. Lymphocytes were sprinkled throughout the tumor in one case but were sparse in the other. The metastatic deposits in the lungs appeared 27 and 2 years, respectively, after the initial presentation and were histologically similar to the original tumors. The FDC nature of the primary and metastatic tumors was confirmed by positive staining with CD21/CD35 cocktail and CD23 and by negative staining for cytokeratin. In one case, in direct continuity with the main tumor, there was a lobulated lesion composed of small lymphocytes punctuated by large cells with vesicular nuclei, histologically reminiscent of thymoma. The large cells were shown by immunohistochemistry to represent FDCs forming complex interconnecting meshworks. It is unclear whether this contiguous mass represents a precursor lesion or an unusual-looking component of the neoplasm. CONCLUSIONS: FDC sarcoma can look deceptively like a thymic epithelial tumor histologically. A correct diagnosis requires a high index of suspicion and immunohistochemical evaluation. The tumor shows a propensity to metastasize to the lungs, which can be delayed until more than 20 years after initial presentation.

Adult↗
PubMed2000

Safety of donors in live donor liver transplantation using right lobe grafts.

HYPOTHESIS: Right lobe donation was advocated for adult-to-adult live donor liver transplantation but the safety of the donor is still a major concern. We hypothesize that right lobe donation is safe if the lowest limit of volume of liver remnant that can support donor survival is known. DESIGN: Retrospective analysis of data collected prospectively. SETTING: Tertiary hepatobiliary surgery referral center. PATIENTS: Twenty-two live donors involved in adult-to-adult right lobe liver transplantation from May 1996 to June 1999. INTERVENTIONS: The right lobe grafts were obtained by transecting the liver on the left side of the middle hepatic vein. Liver transection was performed by using an ultrasonic dissector, without using the Pringle maneuver. The left lobe volume was measured by computed tomographic volumetry and the ratio of left lobe volume to the total liver volume was calculated. MAIN OUTCOME MEASURES: Hospital mortality rate and complication rate. RESULTS: The median blood loss was 719 mL (range, 200-1,600 mL). Only one donor, who had thalassemia, received 1 U of homologous blood transfusion. Postoperative complications included wound infection, incision hernia, and cholestasis in 1 donor whose liver showed 20% fatty change and who had a left lobe-total liver volume of 0.34. Another donor with 15% fatty change in the liver and a left lobe-total liver volume ratio of 0.27 developed prolonged cholestasis. Two other donors with left lobe-total liver volume ratios of 0.27 but with mild steatosis (<5%) did not develop postoperative cholestasis. Postoperative complications also included 1 case of biliary stricture and 1 case of small bowel obstruction. Both complications were adequately treated. There was no donor mortality. All donors are well and have returned to their previous occupations. CONCLUSION: Live donation of right lobe graft for adult-to-adult liver transplantation is safe provided that the residual liver volume exceeds 30% of the total liver volume and the liver itself is normal or only mildly affected by steatosis.

Adolescent↗
PubMed2000

Intestinal inflammatory pseudotumour with regional lymph node involvement: identification of a new bacterium as the aetiological agent.

Inflammatory pseudotumours are the morphological expression of diverse processes such as reactive/reparative, infective, and neoplastic. This paper reports an example of intestinal inflammatory pseudotumour, with identification of a newly characterized bacterium in the lesion. The patient presented with intestinal obstruction. Laparotomy revealed a tumour in the terminal ileum causing stricture, and multiple enlarged regional lymph nodes. Histologically, the tumour and lymph nodes were composed of plump spindle cells disposed in a vague storiform pattern, and associated with lymphocytes and plasma cells. Immunohistochemical studies showed that most of the spindle cells were histiocytes (CD68 positive), prompting a search for a bacterial aetiology, akin to mycobacterial spindle cell pseudotumour. All histochemical stains for micro-organisms were unrewarding. Ultrastructural studies, however, revealed abundant bacteria within the spindle histiocytes. Polymerase chain reaction, using conserved oligonucleotide primers complementary to the 16S rRNA genes of eubacteria, was employed to amplify 16S rRNA gene fragments directly from the involved lymph node tissue. Phylogenetic analysis of the amplified DNA sequences revealed an organism with 99% sequence conformity to Pseudomonas veronii, a bacterium which has hitherto not been implicated in human infection. The importance of searching for an infective agent in inflammatory pseudotumour in the appropriate setting is re-emphasized.

Granuloma, Plasma Cell↗
PubMed2000

Consistent patterns of allelic loss in natural killer cell lymphoma.

Natural killer (NK) cell lymphomas are a group of rare but highly aggressive malignancies. Clinically, they can be divided into nasal NK cell lymphomas, nonnasal NK cell lymphomas, and aggressive NK cell lymphoma/leukemia. To determine the patterns of genetic deletions in these tumors, we performed loss of heterozygosity (LOH) analysis on 15 cases (11 nasal and four nonnasal), and fluorescence in situ hybridization on three cases of aggressive lymphoma/leukemia. A panel of 41 microsatellite loci on chromosomes 6q, 11q, 13q, and 17p were investigated. LOH at chromosomes 6q and 13q was frequently detected in NK cell lymphomas, being found in 80 and 66.7% of cases, respectively. LOH at chromosomes 11q and 17p was less common, being found in 28.6 and 30.8% of cases, respectively. Most tumors showed multiple loci deletions at different chromosomal regions, but several patterns of LOH could be defined. LOH at chromosome 6q was found in 90.9% of nasal NK cell lymphomas, but only in 50% of nonnasal NK cell lymphomas. LOH at chromosome 13q was found in 63.6% of nasal NK cell lymphomas and 75% of nonnasal NK cell lymphomas. For nasal NK cell lymphomas, LOH at 13q was found in 33.3% of cases at presentation, but 100% of cases at relapse. Five tumors showed LOH in only one chromosomal region, involving 6q in three cases (two nasal and one nonnasal), and 13q in two cases (both nonnasal). For the three cases of aggressive NK cell lymphoma/leukemia studied by fluorescence in situ hybridization, DNA loss at 13q14 and 17p13 regions were demonstrated. 17p13 seemed to be more commonly involved in aggressive than nasal and nonnasal NK cell lymphomas. Our results suggested that consistent patterns of LOH could be defined in NK cell malignancies. These deleted loci may contain genes important in the initiation and progression of this lymphoma.

Adult↗
PubMed2000

EUS for detection of occult cholelithiasis in patients with idiopathic pancreatitis.

BACKGROUND: The aim of this study was to evaluate the use of endoscopic ultrasonography (EUS) in detecting occult cholelithiasis and determining a probable etiology in patients classified as having idiopathic pancreatitis by conventional radiologic methods. METHODS: A prospective study was performed in 89 consecutive patients with acute pancreatitis. Transcutaneous ultrasonography (US), CT, or both was performed on all patients within 24 hours of admission. Endoscopic retrograde cholangiopancreatography (ERCP) was performed in all patients with confirmed or suspected biliary pancreatitis. EUS was performed in patients classified as having idiopathic pancreatitis. RESULTS: Cholelithiasis was identified in 64 patients (72%) by conventional radiologic methods. Eighteen patients (20%) were classified as having idiopathic pancreatitis after evaluation by US (all 18 patients), repeated US (9 patients), CT (6 patients) and ERCP (13 patients). EUS performed in these 18 patients revealed small gallbladder stones (1 to 9 mm) in 14 patients; 3 were found to have concomitant choledocholithiasis. All stones were confirmed by subsequent ERCP and cholecystectomy. The remaining 4 patients in whom no etiology was identified had no clinical or radiologic evidence of cholelithiasis at a median follow-up of 22 months. CONCLUSION: Cholelithiasis is detected by EUS in a large number of patients classified as having idiopathic pancreatitis by conventional radiologic examinations. With identification of a biliary cause of acute pancreatitis, treatment can be initiated early, thereby reducing the risk of recurrent pancreatitis with its associated morbidity and mortality. EUS is a valuable diagnostic modality in the management of patients with acute pancreatitis.

Acute Disease↗