Pathology tests are essential for diagnosing and staging cancers, infections, autoimmune diseases, and inflammatory conditions. These tests analyze tissues, cells, and fluids to detect abnormal cellular changes.
📌 Key Pathology Tests & Their Clinical Applications
| Test | Type | Primary Use | Common Conditions Diagnosed |
|---|---|---|---|
| Biopsy | Tissue Sampling | Cancer Diagnosis, Autoimmune Diseases | Breast Cancer, Liver Cirrhosis, Skin Lesions |
| Pap Smear | Cytology (Cells) | Cervical Cancer Screening | HPV Infection, Dysplasia, Carcinoma |
| FNAC (Fine Needle Aspiration Cytology) | Cytology (Needle Sampling) | Masses & Lymph Nodes | Thyroid Nodules, Breast Lumps, Lymphoma |
| Frozen Section | Rapid Tissue Analysis | Intraoperative Cancer Diagnosis | Brain Tumors, Breast Cancer Margins |
| Immunohistochemistry (IHC) | Molecular Pathology | Cancer Subtyping | Breast Cancer (ER/PR), Lymphomas |
| Flow Cytometry | Immunophenotyping | Leukemia & Lymphoma | Acute Myeloid Leukemia, CLL |
| Karyotyping & FISH | Genetic Testing | Chromosomal Disorders, Cancer Mutations | Down Syndrome, CML (BCR-ABL) |
🔬 1️⃣ Biopsy: Gold Standard for Tissue Diagnosis
🔹 What is a Biopsy?
A biopsy is the removal of a small tissue sample for microscopic examination. It helps diagnose cancer, inflammatory diseases, and infections.
🔹 Types of Biopsies & Their Uses
| Biopsy Type | Procedure | Clinical Use |
|---|---|---|
| Excisional Biopsy | Entire lesion is removed | Breast Cancer, Skin Tumors |
| Incisional Biopsy | Part of the lesion is removed | Sarcomas, Oral Cancers |
| Core Needle Biopsy | Thick needle extracts tissue | Breast, Liver, Prostate Tumors |
| Punch Biopsy | Small circular skin sample | Melanoma, Psoriasis |
| Endoscopic Biopsy | Via GI, Respiratory endoscopy | Stomach Cancer, Barrett’s Esophagus |
| Bone Marrow Biopsy | Iliac crest aspiration | Leukemia, Lymphoma, Aplastic Anemia |
🔹 Key Clinical Use:
- Confirms malignancy & tumor grading.
- Assesses organ-specific diseases (Cirrhosis, Glomerulonephritis).
- Bone marrow biopsy is essential for hematological cancers.
👩⚕️ 2️⃣ Pap Smear: Cervical Cancer Screening
🔹 What is a Pap Smear?
A Pap Smear (Papanicolaou test) is a cytological examination of cervical cells to detect pre-cancerous changes & HPV infections.
🔹 How to Interpret a Pap Smear?
| Result | Meaning | Next Step |
|---|---|---|
| Normal | No abnormal cells | Routine screening (Every 3–5 years) |
| ASCUS (Atypical Squamous Cells of Undetermined Significance) | Mild cell changes, unclear cause | HPV Testing or Repeat Pap |
| LSIL (Low-Grade Squamous Intraepithelial Lesion) | HPV-related mild dysplasia | Repeat in 6–12 months |
| HSIL (High-Grade Squamous Intraepithelial Lesion) | Pre-cancerous changes | Colposcopy & Biopsy |
| Cervical Carcinoma | Invasive cancer | Immediate oncology referral |
🔹 Key Clinical Use:
- Early detection of cervical cancer in women aged 21–65 years.
- HPV co-testing improves specificity for detecting high-risk HPV strains.
💉 3️⃣ FNAC (Fine Needle Aspiration Cytology)
🔹 What is FNAC?
FNAC is a minimally invasive method where a thin needle is used to extract cell samples from lumps, nodules, or cysts.
🔹 When to Use FNAC?
| Site | Indication |
|---|---|
| Thyroid | Thyroid nodules, Goiter, Thyroid Cancer |
| Breast | Fibroadenoma vs. Breast Cancer |
| Lymph Nodes | Tuberculosis, Lymphoma, Metastases |
| Liver | Hepatocellular Carcinoma, Liver Abscess |
| Salivary Glands | Parotid Tumors, Sjögren’s Syndrome |
🔹 Key Clinical Use:
- Quick diagnosis of benign vs. malignant tumors.
- Used in superficial and deep-seated organ masses (Thyroid, Lymph nodes, Breast, Liver).
- Less invasive compared to core biopsy but may need confirmation via histopathology.
🔬 4️⃣ Frozen Section: Rapid Intraoperative Diagnosis
🔹 What is a Frozen Section?
A frozen section biopsy is performed during surgery to determine if a mass is benign or malignant and whether margins are clear.
🔹 Clinical Applications of Frozen Section
| Procedure | Use |
|---|---|
| Breast Surgery | Determines if mastectomy or lumpectomy is needed |
| Brain Tumors | Guides neurosurgeons in removing tumor margins |
| Ovarian Tumors | Differentiates benign cysts from carcinoma |
🔹 Key Clinical Use:
- Guides real-time surgical decision-making.
- Helps in ensuring complete tumor removal.
- **Provides results within 15–30 minutes, but final diagnosis requires paraffin section histopathology.
🧫 5️⃣ Immunohistochemistry (IHC) & Molecular Pathology
🔹 What is IHC?
Immunohistochemistry (IHC) is a special staining technique that detects tumor markers & proteins for cancer classification.
🔹 IHC in Cancer Diagnosis
| Marker | Cancer Type | Clinical Use |
|---|---|---|
| ER/PR | Breast Cancer | Determines Hormone Therapy |
| HER2/neu | Breast, Gastric Cancer | Targeted Therapy (Trastuzumab) |
| p53 | Multiple Cancers | Tumor Suppressor Gene Mutation |
| Ki-67 | All Cancers | Tumor Proliferation Rate |
| CD20 | Lymphoma | B-Cell Marker for Lymphoma |
🔹 Key Clinical Use:
- Classifies cancer subtypes & guides personalized therapy.
- Determines HER2/ER status in breast cancer for targeted treatment.
📌 Key Takeaways for Clinical Practice
✅ Biopsy is the gold standard for cancer diagnosis.
✅ Pap smear is essential for cervical cancer screening.
✅ FNAC is a quick, less invasive method for evaluating lumps & nodules.
✅ Frozen section is used during surgery to assess malignancy & margins.
✅ IHC and molecular pathology are crucial for targeted cancer therapy.