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Nature and evolution of arterial thrombus formation
ABSTRACTS OF ANNUAL MEETING
1974
59
one cavity on the right side. The cavities were partly lined by collections of faintly basophilic fungal hyphae which stained poorly by PAS, but strongly by methenamine silver stain. Invasion of pulmonary vascular walls by the hyphae had occurred. Occasional cylindrical arthrospores were seen; these stained well by PAS. Geotrichum candidum was isolated from both ante-mortem and post-mortem material. This agent is usually regarded as a saprophyte on soil, and occasionally as a commensal in man. It is only rarely a primary pathogen. In this case the fungus is a secondary invader, the primary pulmonary lesion probably being asbestosis. Geotrichosis has been reported in gardeners and, although well described elsewhere, this is the first report of pulmonary infection with Geotrichum candidum from New Zealand. NATURE AND EVOLUTION OF ARTERIAL THROMBUS FORMATION
KWAAN,HAUC. and HATEM, &I A. Department of Medicine, Northwcstern University Medical School and the V.A. Research Hospital, Chicago, U.S.A. Platelets have been recognized to play a key role in the initiation and propagation of an arterial thrombus. We devised an in-vivo canine model by which we can study both quantitatively and qualitatively the evolution of a platelet-rich thrombus in carotid and feooral arteries. By monitoring continuous blood flow, the initial adherence of platelets and subsequent growth of thrombus could be followed closely until complete occlusion of flow. Thrombi removed at different stages of development determined by changes in blood flow, were studied by histochemical and immunofluorescent methods, permitting the distinction between platelet, fibrin and cellular components. The following changes could be differentiated: early individually recognizable platelets as adherent masses; swollen platelets with loss of cell boundary; infiltrating leucocyte masses, early light fibrin strands extending into platelet masses; heavy fibrin deposits along with leucocyte and red cell masses. The effect on thrombus formation by various anticoagulants and by platelet inhibitory agents were studied showing their respective influence on the accumulation of platelets and fibrin. We also studied the thrombi removed successfully in patients from arterio-venous fistulae, reconstructive arterial bypasses, Cordis-Dow hollow fiber artificial kidneys and pulmonary emboli, and found similar patterns of platelet and fibrin relationship. We conclude that when thrombus formation takes place in vessels with high rate of blood flow, platelets occupied a dominant role. FROZEN SECTION DIAGNOSIS OF SUSPECTED MELANOMA OF THE SKIN
LITTLE, J. H. Pathology Department and Queensland Melanoma Project, Princess Alexandra Hospital, Brisbane Due to the frequency of malignant melanoma in Queensland urgent frozen section diagnosis of pigmented skin lesions suspected of melanoma has become a routine procedure, second only to breast lumps in frequency. Review of the Department’s experience shows 329 pigmented skin lesions from 316 patients were diagnosed by urgent cryostat section. There were 3 main groups of lesions-about one half were malignant melanomas and about one quarter each were naevi and non-melanocytic lesions. Histological error occurred in 4 cases (1.2%) and in 2 cases of combined naevi resulted in unnecessary surgery. The recognition of the combined naevus is important in avoiding error as 11 tumours in the series were combined naevi. Seven were combined Spitz (juvenile melanoma) and common naevi at the junctional, compound or intradermal stage and 4 were combined blue or cellular blue and common naevi. The error rate of 1.2% is acceptable when compared with published rates of frozen section diagnoses on a wider range of tissues. The diagnosis was withheld in 19 lesions (5.8%) which on paraffin section were predominantly melanomas. The causes were superficial levels of tumour, heavy lymphocytic infiltration, partial tumour regression and unusual cell shape and arrangement in the melanomas. In all 3 groups most of the lesions were less than 15mm diam. and were flat. Nearly 40% of the melanomas were Level I or 11. The majority of the naevi were compound naevi. The non-melanocytic tumours were mainly pigmented basal cell carcinomas and basal cell papillomas. As a result of the frozen section report, further treatment was performed in 83 (52%) of the malignant melanoma cases. I t is concluded that cryostat section diagnosis of malignant melanoma in experienced hands is reliable and is of considerable value to the surgeon.
1974
59
one cavity on the right side. The cavities were partly lined by collections of faintly basophilic fungal hyphae which stained poorly by PAS, but strongly by methenamine silver stain. Invasion of pulmonary vascular walls by the hyphae had occurred. Occasional cylindrical arthrospores were seen; these stained well by PAS. Geotrichum candidum was isolated from both ante-mortem and post-mortem material. This agent is usually regarded as a saprophyte on soil, and occasionally as a commensal in man. It is only rarely a primary pathogen. In this case the fungus is a secondary invader, the primary pulmonary lesion probably being asbestosis. Geotrichosis has been reported in gardeners and, although well described elsewhere, this is the first report of pulmonary infection with Geotrichum candidum from New Zealand. NATURE AND EVOLUTION OF ARTERIAL THROMBUS FORMATION
KWAAN,HAUC. and HATEM, &I A. Department of Medicine, Northwcstern University Medical School and the V.A. Research Hospital, Chicago, U.S.A. Platelets have been recognized to play a key role in the initiation and propagation of an arterial thrombus. We devised an in-vivo canine model by which we can study both quantitatively and qualitatively the evolution of a platelet-rich thrombus in carotid and feooral arteries. By monitoring continuous blood flow, the initial adherence of platelets and subsequent growth of thrombus could be followed closely until complete occlusion of flow. Thrombi removed at different stages of development determined by changes in blood flow, were studied by histochemical and immunofluorescent methods, permitting the distinction between platelet, fibrin and cellular components. The following changes could be differentiated: early individually recognizable platelets as adherent masses; swollen platelets with loss of cell boundary; infiltrating leucocyte masses, early light fibrin strands extending into platelet masses; heavy fibrin deposits along with leucocyte and red cell masses. The effect on thrombus formation by various anticoagulants and by platelet inhibitory agents were studied showing their respective influence on the accumulation of platelets and fibrin. We also studied the thrombi removed successfully in patients from arterio-venous fistulae, reconstructive arterial bypasses, Cordis-Dow hollow fiber artificial kidneys and pulmonary emboli, and found similar patterns of platelet and fibrin relationship. We conclude that when thrombus formation takes place in vessels with high rate of blood flow, platelets occupied a dominant role. FROZEN SECTION DIAGNOSIS OF SUSPECTED MELANOMA OF THE SKIN
LITTLE, J. H. Pathology Department and Queensland Melanoma Project, Princess Alexandra Hospital, Brisbane Due to the frequency of malignant melanoma in Queensland urgent frozen section diagnosis of pigmented skin lesions suspected of melanoma has become a routine procedure, second only to breast lumps in frequency. Review of the Department’s experience shows 329 pigmented skin lesions from 316 patients were diagnosed by urgent cryostat section. There were 3 main groups of lesions-about one half were malignant melanomas and about one quarter each were naevi and non-melanocytic lesions. Histological error occurred in 4 cases (1.2%) and in 2 cases of combined naevi resulted in unnecessary surgery. The recognition of the combined naevus is important in avoiding error as 11 tumours in the series were combined naevi. Seven were combined Spitz (juvenile melanoma) and common naevi at the junctional, compound or intradermal stage and 4 were combined blue or cellular blue and common naevi. The error rate of 1.2% is acceptable when compared with published rates of frozen section diagnoses on a wider range of tissues. The diagnosis was withheld in 19 lesions (5.8%) which on paraffin section were predominantly melanomas. The causes were superficial levels of tumour, heavy lymphocytic infiltration, partial tumour regression and unusual cell shape and arrangement in the melanomas. In all 3 groups most of the lesions were less than 15mm diam. and were flat. Nearly 40% of the melanomas were Level I or 11. The majority of the naevi were compound naevi. The non-melanocytic tumours were mainly pigmented basal cell carcinomas and basal cell papillomas. As a result of the frozen section report, further treatment was performed in 83 (52%) of the malignant melanoma cases. I t is concluded that cryostat section diagnosis of malignant melanoma in experienced hands is reliable and is of considerable value to the surgeon.