Medullary thyroid carcinoma is associated with a risk of nodal involvement, even if neck nodes are not visible on ultrasound. A total thyroidectomy is recommended to remove the affected thyroid tissue, and central neck dissection is indicated to address potential lymphatic spread.
Total thyroidectomy: While a total thyroidectomy is necessary for medullary thyroid carcinoma (MTC) to remove the entire gland, it does not include the assessment and potential removal of central lymph nodes, which can harbor metastases.
c) Total thyroidectomy with lateral and central neck dissection: This option is more extensive than typically required for a 1 cm medullary carcinoma without evidence of lymph node involvement. Start with central node dissection unless there's clear lateral disease.
d) Right hemithyroidectomy: Inadequate for managing MTC. Since MTC can be bilateral and multifocal, a total thyroidectomy is the standard of care.
Q) A 30-year-old female in the 2nd trimester of pregnancy has a 2 cm breast carcinoma with no axillary lymph nodes. What should be the management?
✅ Answer: D. Lumpectomy + axillary dissection + chemo
🔍 Explanation:
In this case, lumpectomy followed by axillary dissection and chemotherapy is the preferred management.
- Axillary dissection is ideally done after Sentinel Lymph Node Biopsy (SLNB)
- Radiotherapy can be given after the termination of pregnancy if necessary.
- Hormonal therapy can also be started after pregnancy if required.
- There is no need to terminate the pregnancy unless absolutely necessary, as modern treatments can be administered with careful planning.
🧠 Key Point: **Axillary dissection** and **chemotherapy** are preferred, with the option for hormonal therapy after pregnancy.
Q) Newborn with abdominal distension on day 2, not passed meconium. There is absent anal orifice. What is the next step? # NEET SS 22
✅ Answer: A. Cross table X ray
🔍 Explanation:
The first step in such cases is to rule out congenital abnormalities of the spine, sacrum, kidneys, and heart.
- The second step is a Cross-table X-ray. If the X-ray shows perineal fistula, perform Anoplasty.
- If the X-ray shows rectal gas below the coccyx, perform a PSARP (Posterior Sagittal Anorectoplasty) with or without a colostomy.
- If the X-ray shows gas above the coccyx with associated defects, perform a colostomy.
🧠 Key Point: Cross-table X-ray is crucial to determine the presence of rectal gas and other associated defects, guiding the next step in management.
Q) The principal energy source for colonocytes is:
✔ Free for all users
A. Glucose
B. Lactate
C. Butyrate
D. Long-chain fatty acids
✅ Answer: C. Butyrate
Butyrate is the primary fuel for colonocytes. It is a short-chain fatty acid (SCFA) produced by the colonic flora when fermenting complex carbohydrates. The colonic epithelium and luminal bacteria form a crucial symbiotic relationship where bacteria produce butyrate, which provides essential nutrition to the colonocytes.
Antibiotics disrupt this balance by reducing bacteria, leading to less butyrate, which negatively affects colonocyte function, often causing diarrhea.
🧠 Key Point: Butyrate, not glucose or lactate, is the key fuel for colonocytes, and its production relies on gut bacteria.
Teaching Points
Short-chain fatty acids (SCFAs): butyrate, acetate, and propionate are produced by bacterial fermentation of dietary fiber.
Butyrate provides ~70% of the energy requirements of colonocytes.
It promotes mucosal integrity, anti-inflammatory effects, and epithelial repair.
Reduced butyrate production is implicated in:
Antibiotic-associated diarrhea
Diversion colitis
Inflammatory bowel disease
High-fiber diets increase SCFA production and improve colonic health.
Why other options are incorrect
A. Glucose — minimal utilization by colonocytes compared to SCFAs.
B. Lactate — intermediate metabolite; not the primary fuel.
D. Long-chain fatty acids — absorbed mainly in the small intestine.
MCQ on Most Common Lymph Node Involved in Prostate Carcinoma
Q) Most common lymph node involved in carcinoma prostate is
✅ Answer: A. Obturator
🔍 Explanation:
The most common lymph node involved in **prostate carcinoma** is the **obturator lymph node**.
Lymphatic spread may occur via lymphatic vessels that pass to the **obturator fossa**, along the sides of the rectum to the lymph nodes near the **internal iliac vein** and in the hollow of the sacrum.
Additionally, lymphatics pass over the **seminal vesicles** and follow the **vas deferens** for a short distance to drain into the **external iliac lymph nodes**.
From the retroperitoneal lymph nodes, the **mediastinal nodes** and occasionally the **supraclavicular nodes** may become implicated.
🧠 Key Point: **Obturator lymph nodes** are the first to be affected in prostate cancer due to the nature of lymphatic drainage from the prostate.
Q) Which of the following does not form a part of Virchow's triad?
a) Endothelial damage
b) Slow blood flow
c) Platelet defects
d) Hypercoagulable state
Correct Answer: c) Platelet defects
Explanation:
Virchow triad (venous stasis, endothelial injury, and hypercoagulability) describes the factors contributing to venous clot formation and thromboembolism.
Platelet defects are associated with arterial thrombosis and not venous.
Virchow is known as "the father of modern pathology" and founder of social medicine.
---
Virchow’s Triad: Unraveling the Factors Behind Thrombosis
1. Endothelial Damage:
Endothelial cells line blood vessels. When injured, they expose tissue factor, initiating clot formation. Seen in atherosclerosis, sepsis, trauma.
2. Abnormal Blood Flow:
Stasis or turbulence promotes clotting. Causes include prolonged immobilization, atrial fibrillation, varicose veins.
3. Hypercoagulability:
A state of increased clotting tendency.
Causes:
• Oral contraceptives, obesity, pregnancy
• Inherited mutations (e.g. factor V Leiden)
• Smoking, malignancy
Most thrombi result from a combination of the above factors. Recognizing the triad aids in prevention and diagnosis of thromboembolic disease.
Q) Most potent cells that present antigen and are distributed throughout the lymphoid and nonlymphoid tissues of the body are?
✅ Answer: A. Dendritic cells
🔍 Explanation: Dendritic cells are specialized macrophages and are considered professional antigen presenting cells (APCs). They are the most potent APCs in the body, distributed widely in both lymphoid and non-lymphoid tissues.
🧠 NK cells are large granular lymphocytes involved in innate immunity. They have cytolytic functions but are not classified as APCs.
🧠 Macrophages and monocytes can present antigens but are less efficient compared to dendritic cells.
🔍 Explanation:
Paclitaxel is a drug that interferes with mitosis. It belongs to the class of drugs that interfere with mitosis.
- Paclitaxel works by stabilizing microtubules and preventing their disassembly, thereby inhibiting cell division.
- Vincristine is also in the same group but it interferes with the formation of microtubules (spindle poison).
- Antimetabolites include drugs like 5-FU, Methotrexate, and Gemcitabine, which interfere with DNA synthesis.
- Drugs that directly damage DNA include Mitomycin, Cisplatin, Oxaliplatin, and Doxorubicin.
- Receptor tyrosine kinase inhibitors include drugs like Imatinib and Gefitinib.
🧠 Key Point: Paclitaxel is primarily classified as a drug that interferes with mitosis, making it a mitotic inhibitor.
Q) Which of the following trace elements deficiency causes impaired glucose tolerance, anemia, neutropenia, and leukopenia?
✅ Answer: B. Copper
🔍 Explanation:
Copper deficiency is associated with impaired glucose tolerance, anemia, neutropenia, leukopenia, and changes in skin and hair pigmentation.
Copper also plays a crucial role in collagen and elastin synthesis, scavenges free radicals, and is linked to fatal arrhythmias in its deficiency.
- **Zinc deficiency** causes growth retardation, immune dysfunction, and delayed wound healing but is not typically linked to significant neutropenia.
- **Molybdenum deficiency** is rare and linked to metabolic disorders but not hematological abnormalities.
- **Selenium deficiency** leads to cardiomyopathy (Keshan disease) and myopathy, but not neutropenia or leukopenia.
🧠 Key Point: Copper plays a vital role in multiple metabolic processes, and its deficiency can cause a range of hematological and metabolic abnormalities.
📘 Reference: MCQs on Nutrition and Perioperative Management