A 35 years old male, with pre-morbid anxious traits & heavy smoker, believes that he has been suffering from ‘lung carcinoma’ for a year, No significant clinical finding is detected on examination and relevant investigation. He continues to stick to his belief despite evidence to the contrary. In the process, he has spent a huge amount of money, time and energy in getting himself unduly investigated. He is most likely suffering from:

**Core Concept**
This question tests the student's understanding of Illness Anxiety Disorder (IAD), a condition characterized by excessive worry about having a serious illness despite medical reassurance and the absence of a diagnosable medical condition. IAD is distinct from hypochondriasis, which is now included under the broader category of IAD in the DSM-5.

**Why the Correct Answer is Right**
The patient in this scenario exhibits classic symptoms of IAD, including excessive worry about having a serious illness (lung carcinoma), preoccupation with the possibility of illness despite medical reassurance, and significant distress or impairment in social, occupational, or other areas of functioning. The patient's anxious traits and heavy smoking may have contributed to his preoccupation with illness, but these factors alone do not explain the severity of his symptoms. The patient's behavior is consistent with IAD, as he has spent a significant amount of time, energy, and resources on investigating his supposed illness.

**Why Each Wrong Option is Incorrect**
**Option A:** This option might be tempting, but it is incorrect because the patient does not have a diagnosable medical condition, which is a key characteristic of IAD. A diagnosis of hypochondriasis would be more appropriate if the patient had a medical condition that was being mismanaged or if the primary concern was the fear of having a specific disease.

**Option B:** This option is incorrect because the patient's symptoms are not primarily related to the fear of having a specific disease (e.g., cancer), which is a characteristic of hypochondriasis. The patient's worry is more focused on the possibility of having a serious illness in general.

**Option C:** This option is incorrect because the patient's symptoms do not meet the criteria for a somatic symptom disorder, which requires the presence of one or more chronic physical symptoms that are distressing and result in significant disruption of daily life.

**Option D:** This option is incorrect because the patient's symptoms do not meet the criteria for a factitious disorder, which requires the intentional production or feigning of physical or psychological symptoms.

**Clinical Pearl / High-Yield Fact**
It is essential to differentiate between IAD and other conditions, such as hypochondriasis, somatic symptom disorder, and factitious disorder. A thorough evaluation of the patient's symptoms, medical history, and behavior is necessary to determine the correct diagnosis.

**Correct Answer:** C.

✓ Correct Answer: B. Hypochondrical disorder