How to make a diagnosis

image of How to make a diagnosis
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Obtaining an accurate pathological diagnosis is an essential requirement for optimizing the treatment of the individual cancer patient and for providing the client with an assessment of likely cancer behaviour and likely prognosis. This chapter deals with cytology; surgical biopsy techniques; submission of histological samples; interpretation of tumour descriptions, tumour grading.

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2.1 Decision tree for cytological diagnosis.
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2.3 Criteria for malignancy: a cluster of cells from an aspirate of a prostatic carcinoma. The cells are displaying marked anisocytosis and anisokaryosis. In some cells the nuclear to cytoplasmic ratio is increased. There are bi- and even multinucleated cells. The nuclei contain prominent, often multiple, nucleoli. (Modified Wright’s stain, original magnification X1000)
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2.4 Mast cell tumour. Histological section from a well differentiated MCT, showing homogenous sheets of mast cells; tumour architecture is not important in diagnosis. (H&E, X20 objective) A fine-needle aspirate from such a tumour is likely to yield a similar population of tumour cells. (Giemsa, X40 objective)
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2.5 In contrast to Figure 2.4 , this histological section from a mixed mammary tumour shows the architectural arrangement of the cells, forming lobules and ducts. This is an important aspect of diagnosis and cannot be represented cytologically. (Giemsa, X20 objective)
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2.6 Making an impression smear.
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2.7 FNA technique for a subcutaneous nodule. The lesion is located and held firmly while the needle is inserted. An air-filled syringe is connected to the hub of the needle and the contents blown on to a clean glass slide. A second clean glass slide is placed gently on top of the sample, allowing the film to spread between the slides, which are then gently drawn apart. See text for full details.
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2.8 Poor smearing technique: the stringy blue streaks reflect DNA material from ruptured cells. (Modified Wright’s stain, original magnification X400) (Courtesy of Clinical Pathology Laboratory, Department of Veterinary Medicine, University of Cambridge)
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2.9 Cytospin preparation of pleural fluid from a cat with a mediastinal mass. (Giemsa, X100 objective)
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2.10 Klima needle for bone marrow aspiration.
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2.11 Bone marrow sampling sites. (1) The dorsal wing of the iliac crest is one of the most common sites used in medium to large dogs. (2) The femur may be sampled via the trochanteric fossa (dog and cat, anaesthesia required). (3) The caudal ischium may be more easily located in overweight dogs.
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2.12 Bone marrow aspiration technique. The needle is inserted, using a twisting action. Bone marrow bubbles into the syringe. Globules of fat and flecks of marrow are visible in the sample. Making the smear. See text for full details.
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2.13 Jamshidi biopsy needle.
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2.15 Skin biopsy punch.
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2.16 Needle core biopsy. Tru-cut needle. With the stylet retracted, the needle is advanced into the lesion. The stylet is advanced to expose the specimen notch, which is then rotated to collect tissue. The outer sleeve is advanced to cover the sample. The sample is removed from the notch. (b–d reproduced from the ). Drawn by S.J. Elmhurst BA Hons (www.livingart.org.uk) and are printed with her permission.
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2.17 Grab biopsy equipment.
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2.18 Options for the evaluation of surgical margins.
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2.19 A typical ellipse of skin from an excisional biopsy of a subcutaneous mass. The subcutaneous tissues are dried with paper towels and painted with indian ink. The tissues are then dipped in acetic acid (white vinegar) to precipitate the ink on to the tissue surface.
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2.20 Gross tumour specimen showing cruciate sections for margins. Typical full-thickness cruciate sections are taken, and the tissue samples are placed into cassettes prior to processing into paraffin blocks.
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2.22 The basic principle of immunohistochemistry.
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2.25 Histological sections showing IHC staining of a histiocytic sarcoma for: vimentin; cytokeratin; lysosyme; CD18. Note that the tumour is negative for cytokeratin.
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