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Biomedical subjects

J K Chan

Publications and source records attributed to J K Chan.

At least 253 records · Page 14Linked to original sources
PubMed1991

Kaposi-like infantile hemangioendothelioma. A distinctive vascular neoplasm of the retroperitoneum.

Retroperitoneal soft-tissue tumors are rare in infancy. In this report, we describe a distinctive hemangioendothelioma occurring in the retroperitoneum of a 10-month-old baby girl. This lesion was complicated by obstructive jaundice, intestinal obstruction, and thrombocytopenia (Kasabach-Merritt syndrome) leading to intracranial hemorrhage. The microscopic features of this tumor, characterized by infiltrative lobules of spindle cells and capillaries, are distinct from those of other well-recognized vasoformative tumors. In some areas, the tumor shows a striking resemblance to Kaposi's sarcoma; criss-crossing fascicles of spindle cells are interspersed with narrow vascular spaces, but PAS-positive hyaline globules are absent. The tumor can also be distinguished from the cellular hemangioma of childhood by its well-formed spindle cell fascicles. Several histologically similar cases have been reported. All of them occurred in the retroperitoneum of infants and were frequently complicated by Kasabach-Merritt syndrome. We therefore propose the designation "Kaposi-like infantile hemangioendothelioma" for this unusual neoplasm.

Autopsy↗
PubMed1991

Are 'dysplastic' and hypogranular megakaryocytes specific markers for myelodysplastic syndrome?

Dysmegakaryocytopoiesis is an integral component of myelodysplastic syndrome (MDS), and has been shown in some studies to be an independent prognostic factor. Megakaryocytic hypogranulation, a feature we have noticed for some time to be fairly common in MDS and acute myeloid leukaemia (AML), has received little attention in the literature as a dysplastic feature of megakaryocytes. This study was performed to determine how frequently this feature was observed in MDS and the specificity of its occurrence. On review of archival materials, hypogranular megakaryocytes were observed in 80.3% of MDS, 30.6% of AML and 1.4% of controls. On the other hand, the other well-recognized dysmegakaryocytopoietic features (hypolobulation, multiple separate nuclei, micromegakaryocyte), though frequent in MDS or AML, were also observed in 20% of controls. We therefore propose including megakaryocytic hypogranulation as a cytological feature of myelodysplasia.

Acute Disease↗
PubMed1991

Malignant lymphoma with myxoid stroma: a new pattern in need of recognition.

We report a case of malignant lymphoma in the soft tissues exhibiting prominent myxoid stromal changes and cord-like cellular arrangement, mimicking the architectural as well as cytological features of myxoid chondrosarcoma, except for the absence of tumour lobulation. The only clue to the possible lymphomatous nature of the lesion was the past history of lymphoma. Immunohistochemical studies showed that this represented a B-cell lymphoma, staining positively for leucocyte common antigen and five B-lineage markers L26, MB2, B1 (CD20), B4 (CD19) and To15 (CD22). We conclude that malignant lymphoma should not be excluded from consideration when one encounters a myxoid tumour.

Adult↗
PubMed1991

Basaloid-squamous carcinoma of the upper aerodigestive tract and so-called adenoid cystic carcinoma of the oesophagus: the same tumour type?

Basaloid-squamous carcinoma of the larynx, pharynx and base of tongue and the so-called adenoid cystic carcinoma of the oesophagus are rare but distinctive tumours associated with a grave prognosis. They occur most commonly in elderly males and present at an advanced stage. Our study of four such laryngeal tumours and five such oesophageal tumours shows that they are histologically and immunohistochemically identical, providing support for the idea that they are the same tumour type. They show a biphasic pattern in which basaloid tumour is intimately associated with a neoplastic squamous component which can be invasive or in situ. The basaloid component is in the form of invasive lobules with frequent comedo-necrosis and hyalinization. The constituent cells possess pale pleomorphic nuclei with frequent mitoses. Immunoreactivity for cytokeratin in the basaloid component is remarkable for its absence or weak and focal nature. Review of the literature shows that only a few cases of 'adenoid cystic carcinoma' of the oesophagus are bona fide examples of adenoid cystic carcinoma as it occurs in the salivary glands, while the others are identical to basaloid-squamous carcinoma of the upper aerodigestive tract. Their distinction is important because genuine adenoid cystic carcinoma is much less aggressive than basaloid-squamous carcinoma.

Actins↗
PubMed1991

Epithelial damage by Helicobacter pylori in gastric ulcers.

On review of 136 consecutive biopsies of benign gastric ulcer, Helicobacter pylori was detected in 78 cases (57.3%). The gastric epithelium colonized by Helicobacter pylori showed a characteristic constellation of changes, including loss of apical mucous portion of individual cells, drop-out of epithelial cells, epithelial pits, erosions and cellular tufts, indicative of cellular injury and regeneration. Among the 58 Helicobacter-negative cases, similar changes were not observed in the ulcer edges, except for two cases which exhibited some cellular tufts. Thus, the topographic association of Helicobacter pylori with epithelial damage in the gastric ulcer edges in more than half of the cases suggests that this organism probably plays an aetiological role in ulcerogenesis, at least in these cases. Furthermore, the epithelial changes are so distinctive that they can serve as a helpful histological indicator for the presence of Helicobacter pylori in gastric biopsies.

Adult↗
PubMed1991

Recently characterized vascular tumours of skin and soft tissues.

This review summarizes the clinicopathological features of a number of vascular tumours that have been characterized only in recent years. These include: glomeruloid haemangioma, a multifocal vascular lesion associated with POEMS syndrome: Kaposi-like infantile haemangioendothelioma, a borderline malignant tumour occurring in the retroperitoneum of infants, mimicking Kaposi's sarcoma histologically; giant cell angioblastoma, characterized by proliferated vessels with a granuloma-like appearance; benign lymphangioendothelioma (progressive lymphangioma), slowly-growing macule or plaque over the trunk or limb, mimicking low-grade angiosarcoma histologically; targetoid haemosiderotic haemangioma, a benign lesion with a distinctive annular appearance and histologically overlapping with benign lymphangioendothelioma; spindle cell haemangioendothelioma, a lesion located mostly in the distal extremities, characterized by cavernous vascular spaces, spindle cells with interspersed narrow vascular channels and scattered plump vacuolated endothelial cells; acquired tufted angioma, characterized by 'cannon-ball' involvement of the dermis by lobules of pericyte-rich capillaries; sinusoidal haemangioma, a distinctive variant of cavernous haemangioma which may be confused with angiosarcoma; and epithelioid angiosarcoma, a highly aggressive tumour of deep soft tissue mimicking metastatic carcinoma and co-expressing endothelial and epithelial markers.

Diagnosis, Differential↗
PubMed1991

Sclerosing mucoepidermoid thyroid carcinoma with eosinophilia. A distinctive low-grade malignancy arising from the metaplastic follicles of Hashimoto's thyroiditis.

Eight cases of a distinctive low-grade carcinoma of the thyroid gland occurring in a background of Hashimoto's thyroiditis are reported. The patients were women presenting with a painless thyroid mass. Grossly, the tumors were white, homogeneous, firm, and usually ill defined. Histologically, strands and small nests of squamoid tumor cells exhibiting mild to moderate nuclear pleomorphism, distinct nucleoli, and pale cytoplasm infiltrated an abundant, dense fibrohyaline stroma. Foci of definite squamous differentiation and small pools of mucin were often found within the tumor nests. The neoplastic cells were immunoreactive for cytokeratin, but not for thyroglobulin or calcitonin. The stroma and many of the tumor islands were infiltrated by eosinophils in all cases. Extrathyroidal extension occurred in five cases and lymph node metastases in one. This tumor seems to arise from the benign squamous nests sometimes associated with mucin deposition found in Hashimoto's thyroiditis and thought to be the result of metaplastic changes of the follicular epithelium. It shares several morphologic features with cases previously reported as mucoepidermoid carcinoma of the thyroid, but it differs from them in other respects. The differential diagnosis includes undifferentiated/squamous cell carcinoma, intrathyroidal thymic carcinoma, and direct extension or metastasis of carcinoma from other organs.

Adult↗
PubMed1990

Low-grade B-cell lymphoma of mucosa-associated lymphoid tissue arising in the thymus. A thymic lymphoma mimicking myoepithelial sialadenitis.

We describe two cases of primary low-grade B-cell lymphoma of the thymus that showed histological features of low-grade B-cell lymphoma arising in mucosa-associated lymphoid tissue (MALT). The appearances most closely resembled MALT lymphoma arising in myoepithelial sialadenitis (MESA). In both cases, the tumor was excised. In one case, there has been no recurrence in 4 years of follow-up without further treatment; in the second case, the tumor has involved an axillary lymph node. Immunohistochemistry showed light-chain restriction in both cases, and the B-cell phenotype was similar to that previously described in MALT lymphomas. The occurrence of MALT lymphoma in the thymus is consistent with the presence of mucosal structures (Hassall's corpuscles) and with recent descriptions of a native B-cell population in this organ. The relationship of this previously undescribed thymic low-grade B-cell MALT lymphoma arising in the thymus has not yet been clarified.

B-Lymphocytes↗
PubMed1990

Sarcomatoid variant of anaplastic large-cell Ki-1 lymphoma.

Although anaplastic large-cell Ki-1 lymphomas can mimic a variety of tumors, a correct diagnosis is usually not difficult to reach if it is recognized that lymphoma cells can assume bizarre and pleomorphic appearances and that the pattern of growth can be purely sinusoidal. We report a unique case of a 45-year-old man presenting with a leg lesion that showed sarcomatoid growth patterns. The subcutaneous/dermal tumor displayed a myxoid stroma reminiscent of myxoid malignant fibrous histiocytoma. In a subsequent lymph node biopsy, a well-developed storiform pattern was formed by interweaving fascicles of plump spindle and oval neoplastic cells, reminiscent of pleomorphic/storiform type of malignant fibrous histiocytoma. The lymphoid nature of the tumor cells was documented by immunoreactivity for leukocyte common antigen, Ki-1 antigen, and the T-cell marker UCHL1. We conclude that the presence of a storiform or myxoid pattern does not disqualify the diagnosis of lymphoma; this possibility should always be pursued in pleomorphic tumors because the treatment is substantially different from that for sarcoma, carcinoma, or melanoma.

Antibodies, Monoclonal↗
PubMed1990

Glomeruloid hemangioma. A distinctive cutaneous lesion of multicentric Castleman's disease associated with POEMS syndrome.

A histologically distinctive cutaneous hemangioma occurring in two patients with biopsy-proven multicentric Castleman's disease associated with POEMS (polyneuropathy, organomegaly, endocrinopathy, M-protein, skin changes) syndrome are reported. The lesions were multiple, and appeared as red to purple papules over the trunk and proximal limbs. Microscopically, ecstatic dermal vascular spaces were seen filled with aggregates of capillaries, resulting in structures reminiscent of renal glomeruli. Interspersed between the blood-filled capillary loops were plump "stromal" cells possessing clear vacuoles and periodic acid-schiff-positive eosinophilic globules. These cells had the immunohistochemical profile of endothelial cells (positivity for factor VIII-related antigen, and negativity for leukocyte common antigen, macrophage marker, and muscle-specific actin), and probably represented immature elements that had accumulated immunoglobulins and other proteinaceous material from the circulation. Because vascular lesions may appear before the full-blown POEMS syndrome develops, we suggest careful evaluation and follow-up of all patients presenting with glomeruloid hemangioma or cherry-type capillary hemangioma with focal glomeruloid features for potential development of this syndrome.

Adult↗
PubMed1990

Congenital juvenile granulosa cell tumour of the testis: report of a case showing extensive degenerative changes.

Juvenile granulosa cell tumour is a rare neoplasm of the testis which occurs predominantly in infancy and which may be associated with sex chromosomal abnormalities. We report an unusual case with deceptive histological features resulting from extensive degenerative changes. In the pedunculated intra-abdominal mass resected from a 1-month-old male baby with 45,X/46,X,iso(Yq) mosaicism, there were multiple large cystic spaces devoid of cellular lining or lined by flat nondescript cells, mimicking various cystic lesions such as multicystic mesothelioma, cystic lymphangioma and cystic dysplasia. The cysts were separated by a highly vascularized fibrous stroma. Only in very rare cysts and the smaller cysts in the region of the pedicle were granulosa cells identified, permitting a diagnosis of juvenile granulosa cell tumour to be made.

Child, Preschool↗
PubMed1990

Placental site nodule.

The immunohistological features of a case of placental site nodule, a cytologically alarming but clinically benign lesion, are reported.

Adult↗
PubMed1990

Hyalinizing trabecular adenoma-like lesion in multinodular goitre.

Hyalinizing trabecular adenoma, a recently characterized variant of thyroid adenoma, is often confused with a variety of lesions because of its unusual histological features (Carney, Ryan & Goellner 1987). We report a case of multinodular goitre in which there were several small nodules showing features of hyalinizing trabecular adenoma and peculiar nuclear rods.

Adenoma↗