Summary of "Exam Recall Series (INI CET Nov '22) - Pathology"

This video by Dr. Ilajan Khandelwal provides a detailed review and analysis of pathology questions asked in the November 2022 INI CET exam. The focus is on key topics, clinical correlations, and high-yield facts essential for exam preparation, especially for INI CET and NEET aspirants.

Main Ideas and Concepts

Importance of Pathology in INI CET: Pathology is a core para-clinical subject with a significant weightage (~25 questions directly, ~30-32 including overlaps with other subjects). Understanding pathology well aids in answering questions from medicine, surgery, and other specialties.
Exam Pattern and Difficulty: Questions were mostly easy, with many previous year questions (PYQs) or topics repeatedly asked over the years. Both morning and evening sessions had similar difficulty levels.
Study Strategy: Emphasis on revising previous 3-4 years’ questions and mastering commonly repeated topics.

Key Topics and Lessons Covered

1. General Pathology

Cellular Aging: Frequently asked; includes sirtuins, calorie restriction, Werner syndrome, Hayflick limit, telomere biology, and telomerase activity.
Cell Injury and Adaptation: Atrophy (especially senile atrophy due to ischemia), inflammation (transmigration, rolling of leukocytes), cytokines, chemical carcinogenesis.
Inflammation: Rolling mediated by selectins, transmigration by PECAM-1 (CD31), chemotaxis, and phagocytosis mechanisms.

2. Neoplasia

Chemical carcinogens and their associated cancers (e.g., diethylstilbestrol with clear cell carcinoma of female genital tract, asbestos with mesothelioma).
Oncogenes and tumor suppressor genes.
Molecular markers and immunohistochemistry (IHC) in diagnosis.

3. Hematology

Leukemias: CML (t(9;22) Philadelphia chromosome, basophilia, imatinib treatment), CLL (smudge cells, CD5+, CD23+), AML, ALL prognostic factors.
Anemias:
- Microcytic hypochromic anemia differential diagnosis (Sideroblastic, Iron deficiency, Thalassemia, Anemia of chronic disease).
- Use of serum ferritin, serum iron, TIBC, peripheral smear, and indices like Mentzer index for differentiation.
Hemophilia A and B (X-linked recessive, factor deficiencies, bleeding types).
Hereditary spherocytosis (family history, MCHC, gallstones, splenectomy effects).
Bone marrow aspirate needles: Jamshidi (biopsy and aspiration), Klima, and Salah needles with distinguishing features.

4. Immunology

Immunodeficiency disorders: Bare lymphocyte syndrome (MHC class II deficiency).
Cytokines secreted by different T-helper cells (Th1 secretes IL-2, IFN-γ; Th2 secretes IL-4, IL-5, IL-13; Th17 secretes IL-17, IL-22).

5. Systemic Pathology

Lung Cancers: - Squamous cell carcinoma (p40, p63 positive, keratin pearls). - Adenocarcinoma (TTF-1, napsin A positive). - Small cell carcinoma (chromogranin, synaptophysin, NSE positive, neuroendocrine features, paraneoplastic syndromes). - Large cell carcinoma and carcinoid tumors. - Malignant mesothelioma (asbestos exposure, long slender microvilli on EM).
Thyroid Cancers: - Papillary carcinoma (orphan Annie nuclei, nuclear inclusions, psammoma bodies, BRAF mutation). - Follicular carcinoma (capsular and vascular invasion). - Medullary carcinoma (amyloid, MEN2 association).
Gastrointestinal Stromal Tumor (GIST): - CD117 (c-KIT) positive, arises from interstitial cells of Cajal, spindle and epithelioid cells, Fletcher’s classification (size and mitotic count for prognosis).
Storage Disorders: - Gaucher disease (crumpled tissue paper cytoplasm, glucocerebrosidase deficiency).
Skin Lesions: - Molluscum contagiosum (umbilicated nodules, Henderson-Patterson bodies).

6. Practical Hematology and Instruments

Identification of bone marrow needles.
Use of Sally’s hemoglobinometer (principle: conversion of hemoglobin to acid hematin).
Thromboelastography (TEG):