Summary
Highlights
This session continues the lab instruction on neoplasia, focusing on six specific slides of malignant epithelial tumors. The slides include invasive ductal carcinoma, bronchial alveolar carcinoma, gastric adenocarcinoma, adenocarcinoma in Barrett's esophagus, adenocarcinoma of the colon, and small cell carcinoma.
Invasive ductal carcinoma is a primary malignant tumor of the breast, presenting as an ill-defined, yellow-white solid mass. Histologically, it's graded using the Nottingham score based on tubular formation, mitosis, and nuclear pleomorphism. The video discusses Grade 1 (small, round nuclei, tubular formation, no mitosis), Grade 2 (increased pleomorphism, prominent nucleoli), and Grade 3 (marked pleomorphism, mitosis, necrosis). It also covers chemotherapeutic importance, including assays for estrogen, progesterone, and HER2/neu receptors, and their implications for treatment protocols like Tamoxifen and Trastuzumab. Different immunochemical subtypes (ER/HER2 status, proliferation index) are described, accounting for various patient populations.
Bronchial alveolar carcinoma, an older term now known as adenocarcinoma in situ, originates from the lung periphery. It is characterized by atypical columnar cells lining the alveolar septa, appearing as a pre-invasive neoplasm.
Gastric adenocarcinoma accounts for 90% of gastric cancers. Risk factors include H. pylori infection, mucosal atrophy, intestinal metaplasia, and exposure to food preservatives like nitrites and benzopyrene. Genetic mutations associated with sporadic cases include APC gene loss-of-function and beta-catenin gain-of-function. Histologically, glandular patterns (intestinal type) and signet ring cells (diffuse type) are observed. Prognostic factors include the number of glands (differentiation), depth of invasion into the muscular layer, and lymph node metastasis.
Barrett's esophagus involves intestinal metaplasia within the esophagus, replacing the normal stratified squamous epithelium. This condition can lead to dysplasia, a risk factor for adenocarcinoma. Risk factors for this malignancy include GERD, Barrett's esophagus itself, H. pylori infection, and genetic mutations like p53 and CDKN2A inactivation. Histological features include atypical glands in back-to-back formation, increased proliferation, intraluminal bridging, and budding.
Adenocarcinoma of the colon typically involves atypical glands with goblet cells, often in a back-to-back pattern with minimal intervening stroma. Sporadic cases are linked to APC gene inactivation (70-80%), while familial forms (HNPCC) are associated with mismatch repair gene mutations (MSH1, MSH2). Other risk factors include low fiber intake and high carbohydrate/fat intake. Tumors can be proximal (right side, bulky, iron deficiency) or distal (left side, napkin-ring constriction, altered bowel movements).
Small cell carcinoma is a highly aggressive lung cancer with a strong link to smoking. It consists of small, round cells similar in size to resting lymphocytes. Immunostaining shows positivity for cytokeratin, chromogranin, synaptophysin, and BCL2 (90%). Key features include nuclear molding (nucleus conforming to adjacent cells) and crushing artifact (dark, elongated nuclei due to compression), often with an azzopardi effect (dark staining of vessel walls from DNA incrustation).