CLINICAL FEATURESOF TUMORS:
LOCAL AND HORMONAL EFFECTSLocal effects of the tumor or its metastasis can be due to pressure or destruction by direct infiltration, and bleeding from ulceration.
Endocrine tumors may produce hormones (commoner in benign than malignant tumors), e-g. adrenocortical adenoma can cause Cushings syndrome and pheochromocytoma can cause hypertension.
CANCER CACHEXIA
Loss of body fat, wasting, and profound weakness is referred to as cancer cachexia.The basis for cachexia is multifactorial:
Loss of appetite.Metabolic changes leading to reduced synthesis and storage of fats and increased mobilization of fatty acids from adipocytes.
Production of cachectin (TNF-alpha) by macrophages, and some tumor cells and possibly other humoral factors can produce the metabolic effects of cachexia.
PARANEOPLASTIC SYNDROMES:
DefinitionSymptoms not directly related to the primary tumor or its metastasis or elaboration of hormones indigenous to the tissue from which the tumor arose.
Paraneoplastic syndromes may be the earliest manifestation of a tumor and may mimic distant spread.
The commonest syndromes include:
Endocrinopathies: Ectopic hormone or hormone-like factors production by nonendocrine cancers e.g., parathormone by squamous cell carcinoma of the lung, inappropriate ACTH or ADH release by small cell cancers of the lung, polycythaemia due to erythropoetin production by renal cell carcinoma , hypoglycemia due to production of insulin or a like factor by hepatocellular carcinoma .
Mypathy, neuropathy, encephalopathy or myesthenic syndromes as in lung cancers possibly due to immunological mechanisms.
Hypertrophic osteoarthropathy and finger clubbing in lung cancer (unknown cause).
Vascular and hematological changes:Thrombophlebitis migrans (In pancreatic and gastric cancer), due to production of mucins by the tumor stimulating coagulation.
Non-bacterial thrombotic endocarditis and DIC, in advanced cancers due to hypercagulibility.
Anemia in thymic neoplasms (Unknown cause).
Nephrotic syndrome in various cancers mediated by tumor antigens and immune complexes.
LABORATORY DIAGNOSIS OF CANCER:I. HISTOLOGICAL AND CYTOLOGICAL METHODS
A. Histological methodsHistological examination is the most important method of diagnosis.
Proper diagnosis is aided by:
Availability of all relevant clinical data.
Adequate preservation and sampling of the specimen.
Frozen specimens are sometimes required for hormone or cell surface receptor study.
A-Routine (H&E)
staining is the corner stone of tissue-based diagnosis. The process stains thin tissue sections so that pathologists can visualize tissue morphology. The process uses a haematoxylin dye to stain cell nuclei (and other parts) blue and an eosin dye to stain other structures pink or red. Properly applied, this technique provides exceptional detail of tissue structure and the makeup of the cells. This detail is required for tissue-based diagnosis, particularly in the detection and classification of cancer. Special stains use a variety of dyes and techniques to stain particular tissues, structures or pathogens (such as bacteria) to assist pathologist with tissue-based diagnosis.
The hematoxylin and eosin stain (H&E) is the most widely used stain in histology and histopathology laboratories. When it is properly performed it has the ability to demonstrate a wide range of normal and abnormal cell and tissue components and yet it is a relatively simple stain to carry out on paraffin or frozen sections. In histopathology a high proportion of cases can be diagnosed by an experienced pathologist using an H&E stain alone.
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B- Special stains:
There are very numerous special stains other than H&E stain used for application of neoplastic and non-neoplastic conditions .The most important special stains:
PAS stain (periodic acid-schiff) stain , used for stain of glycogen, fungi and parasites.
Congo-red stain for amyloid.
Reticulin stain for reticular fibers applied in cases of severe dysplasia, stain the basement membrane for any minimal breached.
Quick frozen section
Quick frozen section is valuable tool used to rapidly prepare slide for microscopical examination, frozen section is used in clinical and research settings, in surgical pathology frozen sections are routinely used for rapid interoperative diagnosis, the slides prepared by frozen section can be utilized for morphological, immunohistochemical and molecular method.Clinical application of frozen section teqnique:
1-Rapid diagnosis e.g., of breast cancer2- Define free margin of excision as in CA colon.