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Biomedical subjects

J K Chan

Publications and source records attributed to J K Chan.

At least 235 records · Page 13Linked to original sources
PubMed1992

Aggressive angiomyxoma. A report of four cases occurring in men.

Aggressive angiomyxoma is a distinctive, locally aggressive but nonmetastasizing soft tissue tumor of the pelvic soft tissues and perineum. This rare tumor occurs almost exclusively in adult women. We report four cases occurring in adult men, one each located in the scrotum, inguinal region, spermatic cord, and pelvis. The tumors were infiltrative, and were composed of fibromyxoid matrix sparsely populated by bland-looking spindled and stellate cells with delicate cytoplasmic processes. There were haphazardly scattered small and large blood vessels, some of which exhibited hypertrophy or hyalinization of the wall. Immunohistochemically, the stromal cells stained consistently for vimentin and variably for muscle-specific actin, but not alpha-smooth muscle actin, desmin, and S-100 protein. None of the four tumors recurred in follow-up times from 11 months to 6 years, although two previously reported cases in men recurred. This uncommon tumor occurring around the genital region in men merits wider recognition because of its potential for recurrence. It should be distinguished from benign tumors with low risk of recurrence on one hand, and from malignant myxoid tumors with metastatic potential on the other.

Adult↗
PubMed1992

Bacillary angiomatosis. A "new" disease with a broadening clinicopathologic spectrum.

Bacillary angiomatosis (BA) is a reactive vasoproliferative lesion occurring almost exclusively in immunocompromised individuals in response to infection by a bacillus closely related to Rochalimaea quintana. The commonest site of involvement is the skin, in the form of multiple erythematous nodules, but bacillary angiomatosis can also present in a wide variety of sites such as soft tissues, bone, lymph node, liver and spleen. Some patients may present with persistent fever and bacteraemia. Bacillary angiomatosis is characterized histologically by proliferation of blood vessels lined by plump endothelium, associated with an interstitial eosinophilic or amphophilic material formed by aggregated bacilli, best demonstrated by the Warthin-Starry stain. A heavy infiltrate of neutrophils is frequently, but not invariably, present. In the liver and spleen, there may be in addition features of peliosis. It is important to be able to diagnose bacillary angiomatosis correctly because prompt treatment with antibiotics is potentially life-saving.

Acquired Immunodeficiency Syndrome↗
PubMed1991

Anaplastic large cell Ki-1 lymphoma of bone.

Anaplastic large cell Ki-1 lymphoma is an uncommon type of non-Hodgkin's lymphoma that rarely presents primarily in the bone. Three such cases are reported. All patients were young and had bone pain; one had paraparesis as a complication of collapse of the thoracic vertebral body. The involvement was either monostotic or polyostotic. Radiologically, the lesions were lytic and had ill-defined borders. Histologically, the large neoplastic cells had pleomorphic bizarre nuclei, prominent nucleoli, abundant deeply amphophilic cytoplasm, and paranuclear pale hof. They were admixed with variable numbers of inflammatory cells. One case each was of T-cell, B-cell, and non-T non-B lineage. All three cases showed excellent responses to chemotherapy with or without radiation therapy. Recognizing the lymphomatous nature of this highly pleomorphic tumor is important because of its potential curability with appropriate chemotherapy.

Adult↗
PubMed1991

The acute lupus hemophagocytic syndrome.

OBJECTIVE: To characterize an unusual mode of presentation of systemic lupus erythematosus: acute and severe pancytopenia related to reactive hemophagocytosis. DESIGN: Retrospective case series. SETTING: Two general community hospitals in Hong Kong. PATIENTS: Six patients presenting with a reactive hemophagocytic syndrome, identified over a 3.5 year period, diagnosed with systemic lupus erythematosus according to the criteria of the American Rheumatism Association. RESULTS: In addition to severe pancytopenia and marrow hemophagocytosis, other characteristic features were fever, hypocomplementemia, high antinuclear antibody titer, and cutaneous and visceral vasculitis. There was no evidence of an underlying infection. The pancytopenia responded dramatically to treatment with steroids. CONCLUSION: Recognition of the acute lupus hemophagocytic syndrome and distinction from an infection-associated hemophagocytic syndrome is important because it responds well to steroid therapy. The evaluation of patients presenting with a hemophagocytic syndrome should include serologic tests for systemic lupus erythematosus.

Acute Disease↗
PubMed1991

Anaplastic large cell Ki-1 lymphoma involving bone marrow: marrow findings and association with reactive hemophagocytosis.

This report describes the bone marrow findings in four patients whose marrow was involved by anaplastic large-cell Ki-1 lymphoma, an uncommon event in this type of lymphoma. In the marrow aspirate smears, the involvement was subtle, and was in the form of isolated large cells with irregular nuclear configuration, coarse chromatin, prominent nucleoli, and basophilic cytoplasm which might be vacuolated. One case showed paradoxically massive involvement in the trephine biopsy taken from the same site as the marrow aspirate. Reactive histiocytic proliferation with hemophagocytosis was also present. Since marrow aspirate or biopsy may be the first pathologic specimen examined in patients having anaplastic large-cell Ki-1 lymphoma, it is important to be able to recognize the small population of neoplastic cells, which should lead to prompt treatment or further investigations as deemed necessary.

Adolescent↗
PubMed1991

Concurrent acute myeloid leukemia and systemic mastocytosis.

A 51-year-old woman presented with concurrent systemic mastocytosis and acute myeloid leukemia associated with a clonal karyotypic anomaly of t(8;21). Cytochemical, histologic, and cytogenetic studies helped in the distinction from a recently described entity: acute myeloid leukemia with marrow basophilia. Although the leukemia responded well to aggressive chemotherapy, the mastocytosis component worsened, illustrating the inherent resistance of mastocytosis to chemotherapy.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1991

Tumors of the neck showing thymic or related branchial pouch differentiation: a unifying concept.

A number of rare tumors occurring in the soft tissues of the neck and the thyroid gland, reported in the literature under a variety of designations, show complete to partial histologic resemblance to the fetal, mature, or involuted thymus and mediastinal thymomas. This family of tumors spans a range of histologic appearances and behaviors from completely benign lesions to metastasizing malignant tumors. After reviewing the previously reported and new cases, we have been able to delineate four reasonably well-defined clinicopathologic entities within this spectrum. On the benign end is "ectopic hamartomatous thymoma," which occurs in the soft tissues of the lower neck. It is characterized by spindle epithelial cells, solid or cystic epithelial islands, and adipose cells which intermingle haphazardly to impart a hamartomatous quality. In the middle of the spectrum are the ectopic cervical thymomas which are usually benign, but can sometimes be locally invasive and can exceptionally metastasize. They are histologically identical to mediastinal thymomas, and residual ectopic thymus is not uncommonly identifiable in the periphery of the tumor. On the malignant end are tumors we have designated as "spindle epithelial tumor with thymus-like differentiation" (SETTLE) and "carcinoma showing thymus-like differentiation" (CASTLE). Tumors of the SETTLE type occur in the thyroid gland of young patients, and are highly cellular tumors comprised of compact bundles of long spindle epithelial cells which merge with tubulopapillary structures and/or mucinous glands. Tumors of the CASTLE type are histologically similar to thymic carcinoma of the lymphoepithelioma or squamous cell variety. We postulate that this family of tumors arises either from ectopic thymus or remnants of branchial pouches which retain the potential to differentiate along the thymic line.

Adult↗
PubMed1991

Polymorphous low grade adenocarcinoma of the palate in a child.

We report a case of polymorphous low grade adenocarcinoma involving the palate of a 12-year-old girl, the first example of this tumour occurring in the paediatric age group. The tumour displayed infiltrative growth, neural invasion, variegated histological patterns, and minimal cytological atypia. The patient remained disease-free four years after wide local excision of the tumour. The distinction of polymorphous low grade adenocarcinoma from pleomorphic adenoma and adenoid cystic carcinoma is also discussed.

Adenocarcinoma↗
PubMed1991

Primary mucoid adenocarcinoma of the larynx.

Mucous glands carcinomas of the larynx are rare, with most being represented by 'non-specific' adenocarcinoma and adenoid cystic carcinoma. Here we report a unique case of mucoid adenocarcinoma of the larynx occurring in a 46-year-old woman. Despite the presence of regional lymph node metastasis, she remained well four years after surgery.

Adenocarcinoma, Mucinous↗
PubMed1991

Dietary alpha-linolenic acid is as effective as oleic acid and linoleic acid in lowering blood cholesterol in normolipidemic men.

The effect of dietary oleic acid (OA), linoleic acid (LA), and linolenic acid (LNA) on plasma lipid metabolism was studied in eight normolipidemic men. A mixed-fat diet composed of conventional foods was fed during 6-d pre- and post-experimental periods. The same basic diet but with 75% of the fat (26% of total energy) provided by sunflower and olive; canola; soybean; and sunflower, olive, and flax oils was fed during four 18-d experimental periods. Mean plasma total cholesterol (-18%), low-density-lipoprotein-cholesterol, (-22%) and very-low-density-lipoprotein-cholesterol (-41%) concentrations were significantly (P less than 0.004) lower after the experimental diets than after the mixed-fat diet. Mean serum apolipoprotein B (-19%) and apolipoprotein A-I (-9%) concentrations were also significantly (P less than 0.0007) lower after the experimental diets. The experimental diets were equally effective in lowering total and lipoprotein cholesterol and apolipoprotein concentrations in plasma, indicating that dietary OA, LA, and LNA were equally hypocholesterolemic.

Adult↗
PubMed1991

Papillary carcinoma of thyroid with exuberant nodular fasciitis-like stroma. Report of three cases.

Three examples of an unusual morphologic variant of papillary thyroid carcinoma (PTC) are reported. The presence of a prominent stromal component resulted in low-power microscopic appearances resembling fibroadenoma, phyllodes tumor, or fibrocystic disease of the breast in two cases. The carcinomatous component grew in the form of anastomosing narrow tubules, clustered glands, solid sheets with or without squamous differentiation, and/or papillae, and exhibited the typical nuclear features of PTC. The abundant stroma had a nodular fasciitis-like quality and was composed of short fascicles of spindle cells separated by varying amounts of mucoid matrix, collagen, and extravasated red blood cells; this was interpreted as an exuberant mesenchymal reaction to the carcinoma. The importance of recognizing this variant of PTC is that, when one encounters a fibroproliferative lesion of the thyroid, a diligent search should be made for papillary carcinoma. This variant also must be distinguished from the vastly more aggressive papillary carcinomas with anaplastic transformation and the so-called carcinosarcomas.

Adult↗
PubMed1991

Metastatic carcinoma in lymph nodes simulating "syncytial variant" of nodular sclerosing Hodgkin's disease.

The authors report the histories of two patients with undifferentiated carcinoma metastatic to lymph nodes simulating the "syncytial variant" of nodular sclerosing Hodgkin's disease. One of the patients initially was treated for Hodgkin's disease, but the clinical evolution was more typical of carcinoma. Both lesions were characterized histologically by noncohesive aggregates of large neoplastic cells with abundant eosinophilic cytoplasm and conspicuous nucleoli. Although cells compatible with diagnostic Reed-Sternberg cells were identified in an "appropriate" cellular background in both patients, the diagnosis of carcinoma was supported by intense cytokeratin immunoreactivity. Subtle histologic clues that should suggest the possibility of metastatic carcinoma in a patient whose morphologic data suggests the syncytial variant of nodular sclerosing Hodgkin's disease include sinus infiltration, phagocytosis of neutrophils by tumor cells, marked nuclear anaplasia, and the presence of spindle-shaped tumor cells.

Adult↗
PubMed1991

Histopathology of bacillary angiomatosis of lymph node.

Bacillary angiomatosis, a recently characterized pseudoneoplastic vascular proliferation caused by a bacterium identical or related to the cat-scratch disease bacillus, usually presents as cutaneous lesions. We report the histologic findings of this disease involving the lymph nodes of two immunocompromised patients. The lymph nodes showed patchy involvement by coalescent nodules of proliferated blood vessels lined by plump endothelial cells with pale cytoplasm. There were foci exhibiting mild to moderate nuclear atypia. Although neutrophil infiltration was prominent in one case, it was minimal in the other. The interstitium was formed by pink-staining material in hematoxylin-eosin-stained sections, and this proved to be aggregated bacilli on Warthin-Starry stain. Recognition of this potentially fatal disease is important because it is curable with antibiotics.

Adult↗
PubMed1991

Vascular transformation of sinuses in lymph nodes. A study of its morphological spectrum and distinction from Kaposi's sarcoma.

Vascular transformation of lymph node sinuses (VTS) is characterized by conversion of nodal sinuses into capillary-like channels, often accompanied by fibrosis. A detailed study of this entity, based on 76 cases, showed that the morphologic spectrum was much broader than that originally described. The vasoproliferative process caused variable expansion of the subcapsular, intermediate, and medullary sinuses of the lymph nodes and involved single or multiple lymph nodes in a diffuse or segmental fashion. The proliferated vessels formed anastomosing narrow clefts, rounded spaces of different sizes, plexiform channels, or solid spindled to plump cellular foci and often were associated with variable degrees of sclerosis. The vascular spaces were empty, filled with lymph-like fluid, congested with blood, or occasionally thrombosed; extravasation of red cells was common. Several patterns were commonly observed in an individual case. Less common features included perivascular fibrin deposition and the presence of eosinophilic globules. Vascular thrombosis was identified only rarely in extranodal vessels available for histologic assessment. The more cellular forms of this vascular transformation may be mistaken for Kaposi's sarcoma, but can be distinguished from it by the pure sinusoidal distribution, a lack of well-formed spindle cell fascicles, the associated fibrosis, the maturation of the spindle cells into well-formed vascular channels toward the capsular aspect, and the failure of this process to involve the capsule itself, which is frequently affected by Kaposi's sarcoma.

Adolescent↗