## **Core Concept**
Pulmonary sarcoidosis is a systemic granulomatous disease that commonly affects the lungs. It is characterized by the formation of non-caseating granulomas in various organs, most frequently the lungs and lymph nodes. The etiology of sarcoidosis remains unknown, but it is believed to result from a combination of genetic susceptibility and environmental triggers.

## **Why the Correct Answer is Right**
The correct answer, **D**, states that pulmonary sarcoidosis often presents with bilateral hilar lymphadenopathy (BHL) on chest radiography, and it can also cause lung parenchymal abnormalities. The disease typically affects the lungs in 90% of cases, with symptoms ranging from asymptomatic to severe respiratory distress. The presence of non-caseating granulomas on histopathology is diagnostic.

## **Why Each Wrong Option is Incorrect**
- **Option A:** This option is incorrect because while pulmonary sarcoidosis can present with a wide range of symptoms, it is often asymptomatic and detected incidentally on chest radiographs showing BHL.
- **Option B:** This option is incorrect as it inaccurately describes a characteristic feature or diagnostic criterion for pulmonary sarcoidosis.
- **Option C:** This option is incorrect because it does not accurately represent a defining feature or common presentation of pulmonary sarcoidosis.

## **Clinical Pearl / High-Yield Fact**
A key clinical pearl is that pulmonary sarcoidosis often presents with **bilateral hilar lymphadenopathy (BHL)** on chest X-ray, which is a classic radiographic finding. Additionally, the disease can cause erythema nodosum, a type of skin inflammation, and ocular manifestations. A useful mnemonic for sarcoidosis symptoms is "CAUSE": C - Cardiac, A - Arthritis, U - Uveitis, S - Skin, E - Eyes and Erythema nodosum.

## **Correct Answer:** D.