Summary: Episode 92: Learn the difference between carcinoma, sarcoma, mesenchymal tumors, oncogenesis, and the protooncogenes.<br> <br> NEOPLASIA<br> I. Nomenclature: Benign vs. malignant<br> A. Difference between benign and malignant cancer:<br> Main difference – Benign usually does not metastasize, malignant has the capacity to metastasize. Exception: B9 tumor that metastasize: invasive mole (metastasize to lungs, but goes away).<br> B. Overview of Neoplasia<br><br> <br> a) MC skin cancer INVADES but does not metastasize? basal cell carcinoma.<br> b) MC B9 tumor in woman is MC located in which organ? Uterus – it’s a leiomyoma; tumor of smooth muscle!<br> c) Fibroids – smooth muscle; become very hard<br> d) MC B9 tumor in male (yellow) = lipoma<br> e) B9 tumor of glands = adenomas (ie adrenal adenoma – thin adrenal cortex b/c it is functional; it could be making cortisol, therefore suppressing ACTH, and the zone fasiculata and reticularis would undergo ATROPHY…leads to Cushing’s. If tumor secreting mineralocorticoids – it is Conn’s syndrome, causing atrophy of the zone glomerulosa (GFR – salty sweet sex)<br> f) Tubular adenoma = MC precursor lesion for colon cancer (looks like strawberry on a stick)<br> C. Carcinoma vs. sarcoma<br> 1. Carcinoma<br> Malignancy of epithelial tissue (3 epithelial tissues – squamous, glandular, and transitional)<br> a) Squamous carcinoma – how to recognize? Little swirls of increased redness (bright red) called squamous pearls;<br> b) Glandular carcinoma – Round glands, with something in the middle = adenocarcinoma<br> c) Transitional cell carcinoma – from bladder, ureter, renal pelvis (from genital urinary tract) – all with transitional epithelium. Therefore, 3 carcinomas = squamous, adenocarcinoma, and transitional cell carcinomas.<br> d) Example: Malignant melanoma – first step in management? Excision (b9 version = nevus), both are derived from melanocytes. This is the most rapidly increasing cancer in the USA, not MC. They are S-100 Ag “+” tumors – aput tumors<br> e) Aput Tumors: S-100 Ag “+” tumors – aput tumors; aput is precursor uptake decarboxylation, meaning that they are of neurosecretory or neural crest origin. Therefore, on EM, have neurosecretory granules. S-100 Ag is used to stain things of aput origin or neural crest origin (most, not all, will take up that Ag).<br> Examples of aput tumors: melanoma; small cell carcinoma of the lung; bronchial carcinoid; carcinoid tumor at the tip of the appendix; neuroblastoma (secretory tumor), ie 2 y/o with tumors all over skin, and on biopsy, it is S-100 “+”, tumor was from adrenal medulla, metastasize to skin.<br> 2. Sarcomas<br> Sarcomas are malignancy of MESENCHYMAL tissue (not epithelial).<br> <br> * Sarcoma of smooth muscle = leioymyosarcoma;<br> * Striated muscle = rhabdomyosarcoma;<br> * Fat = liposarcoma; (these are malignancies of mesenchymal tissue, while carcinoma’s are of epithelial tissue).<br> <br> Examples:<br> a) Bone, see metaphysis, see Codman’s triangle, and sunburst appearance on x-ray b/c this tumor actually makes bone. Dx = osteogenic sarcoma (bone making sarcoma).<br> b) Biopsy from girl having necrotic mass coming out of her vagina, Vimentin and keratin “-“, and desmin “+”, dx? Embryonal rhabdomyosarcoma (see striation of muscle). This is the MC sarcoma of children (vagina in little girls and penis in little boys).<br> c) Movable mass at angle of jaw = mixed tumor (in parotid); ‘mixed’ b/c two histologically have two different types of tissue but derived from SAME cell layer (not a teratoma, which is from three cell layers),. MC overall salivary gland tumor (usually b9) = mixed tumor.<br> d) Teratoma = tooth, hair, derived from all three cell layers (ectoderm, mesoderm, and endoderm) Aka germ cell tumors – b/c they are totipotential, and stay midline. Ex. anterior mediastinum, or pineal gland; therefore, teratomas are germ cell, midline tumors.<br>
