On the welcome page of the dictionary, three major sections are shown: Normal tissues, Cancer and Cell structure. Below the image of each section are links to introductory texts for i) normal tissue histology, ii) hallmarks of cancer, and iii) cell structure overview. For the cancer-section there is also a link to current cancer statistics (incidence, survival, etc) for Sweden and the rest of the world. Within each section there are direct links to histology descriptions of different tissue types and tumor forms as well as descriptions of cell structures.
For the 'Tissue & cell types' and 'Tumor' sections, tissue-slides stained with hematoxylin and eosin (HE) are shown at three different levels of magnification. On the top level, an overview of the whole tissue-sample is shown with boxes in black indicating where zoomed-in representative parts of the tissue are available for viewing. Clicking on these boxes will zoom in on that part to show tissue structures, cells and features in greater detail. Throughout these sections, arrows indicate relevant tissue structures, cell-types and other features.
For the 'Cell structure' section, immunofluorescent images of formaldehyde-fixed cell lines are shown. The various cell structures that are demonstrated are always shown in the green channel using an antibody found in the Human Protein Atlas. The antibody name is linked to the subcellular location summary page of the target gene. The other channels: nucleus, microtubules and endoplasmic reticulum, are always shown in the blue, red and yellow channels, respectively. The channels can be toggled on and off by clicking on the respective coloured button above the image. When applicable, the immunofluorescent images are complemented by immunohistochemically stained cells where the location of the particular cell structure is shown in brown.
A common feature for all sections is that a general descriptive text about the tissue, tumor-type or cell structure is provided when browsing a particular topic.
Thyroid cancer is fairly common, with an annual incidence ranging from 0.5 to 10 per 100,000 in various populations. Throid cancer is two to four times as frequent in women as in men. The most common form of thyroid cancer is papillary carcinoma (70-80%), followed by follicular carcinoma (10-20%), medullary carcinoma (5-10%) and anaplastic carcinoma (2-10%). Classification according to WHO subdivides thyroid tumors into several different subtypes dependent on histological features. Thyroid tumors can also be classified according to aggressiveness into low-grade malignant, intermediate-grade malignant and high-grade malignant.
The prognosis is good for the major forms of thyroid cancer, with a 10-year relative survival rate of 98% for papillary carcinoma, 92% for follicular carcinoma, and 80% for medullary carcinoma. Besides age, where young patients have a considerably better prognosis, the size of the primary tumor and the tumor stage are the most significant prognostic factors.
Papillary thyroid carcinoma is defined as a malignant epithelial tumor. Microscopically the tumor shows evidence of follicular cell differentiation, typically with papillary and follicular structures as well as characteristic changes in tumor cell nuclei. The key to an accurate diagnosis are nuclear characteristics, including a ground glass appearance, large size, pale staining and irregular outline with deep grooves and pseudoinclusions. Papillary thyroid carcinoma is an indolent cancer, with an excellent long-term prognosis, despite a propensity to invade locally and to spread metastatically to regional lymph nodes. Distant metastases are uncommon.
Follicular carcinoma shows follicular differentiation but lacks the diagnostic features of papillary carcinoma. The incidence of follicular carcinoma is higher in areas of endemic goiter and iodine deficiency appears to be the main contributing risk factor. In contrast to papillary carcinoma, the main mode of metastatic spread is hematogeneous rather than through the lymphatic system. Follicular carcinoma is typically delimited by a fibrous capsule surrounding tightly packed follicles, trabeculae or solid sheets of tumor cells. Tumor cells are often cuboidal with dark or pale staining nuclei with inconspicuous nucleoli. Occasional follicular carcinomas may exhibit nuclear pleomorphism.
For most thyroid tumors, diagnosis can be established by microscopic examination alone, although immunohistochemistry plays an important role in tumors exhibiting unusual morphological features. Antibodies used in diagnostics of thyroid tumors include thyroglobulin (TG), calcitonin (CALCA) and thyroid transcription factor (TTF1).
