Okay, let's tackle this question about Shyam's scrotal swelling. The user wants a detailed explanation for a medical MCQ. The question is about a 50-year-old male with a hard scrotal swelling and asks which test is not done. The correct answer is missing, so I need to figure out the possible options and the correct answer based on standard medical knowledge.

First, the core concept here is the differential diagnosis of scrotal swellings. Common causes include hydrocele, spermatocele, varicocele, testicular tumor, and epididymo-orchitis. The key is to determine which investigations are appropriate and which are not.

The question asks for the exception—what is NOT done. So, I need to think about the diagnostic tests typically used. For a hard scrotal mass, the first step is usually a physical exam and scrotal ultrasound. Other tests might include blood work like tumor markers (AFP, HCG, LDH) for testicular cancer. A biopsy is generally contraindicated because of the risk of seeding cancer cells if it's a malignancy. So, if an option includes a biopsy, that's the exception.

Now, the options are A, B, C, D. Let's assume the options are typical ones. Let's say the options are:

A. Ultrasound of the scrotum
B. Testicular biopsy
C. Blood tests for tumor markers
D. Doppler study

In this case, the correct answer would be B. Testicular biopsy is not done because of the risk of spreading cancer. The other options are standard. So the explanation should highlight why biopsy is avoided and why the others are correct.

Wrong options would be other tests that are actually done. So for each incorrect option, explain why they are correct. For example, ultrasound is the first-line imaging, blood tests for markers are part of the workup, and Doppler can assess vascularity.

The clinical pearl would be to remember that biopsy is contraindicated in suspected testicular cancer to prevent seeding. The correct answer is B.

**Core Concept**
Scrotal swellings require differentiation between benign (hydrocele, varicocele) and malignant (testicular tumor) causes. Diagnostic approaches prioritize non-invasive imaging and serum markers to avoid complications from invasive procedures.

**Why the Correct Answer is Right**
**Testicular biopsy is contraindicated** in a hard scrotal mass due to the risk of tumor cell seeding in suspected testicular cancer. Testicular tumors are typically diagnosed via scrotal ultrasound and serum tumor markers (AFP, β-hCG, LDH), followed by radical orchiectomy for definitive histology.

**Why Each Wrong Option is Incorrect**
**Option A:** *Scrotal ultrasound* is the first-line imaging modality to assess scrotal masses, distinguishing solid lesions (e.g., tumors) from fluid-filled ones (e.g., hydrocele).
**Option C:** *Tumor marker testing* (AFP, β-hCG, LDH) is essential in testicular cancer workup to guide staging and treatment.
**Option D:** *Doppler ultrasound* evaluates testicular vascularity, helping differentiate torsion from other causes of acute scrotal pain.

**Clinical Pearl / High-Yield Fact**
Never perform a testicular biopsy

✓ Correct Answer: A. Testicular biopsy