A man injured his eye in an accident. After two weeks his other developed minor signs of anterior uveitis. Histologic sections of the traumatized eye shows Dalen-Fuchs nodules. Diagnosis is
**Core Concept**
The Dalen-Fuchs nodule is a characteristic histopathological finding associated with sympathetic ophthalmia, a rare but serious inflammatory condition affecting the eye. It is a granulomatous reaction occurring in the choroid between the retinal pigment epithelium and Bruch's membrane.
**Why the Correct Answer is Right**
Sympathetic ophthalmia is a bilateral granulomatous uveitis that occurs in response to a penetrating injury to one eye, leading to the activation of the immune system and subsequent inflammation in the uninjured eye. The Dalen-Fuchs nodule is a hallmark of this condition, composed of epithelioid cells and lymphocytes. This reaction is thought to be mediated by the breakdown of the blood-ocular barrier and the subsequent recognition of ocular antigens by the immune system. The formation of Dalen-Fuchs nodules is a key feature that distinguishes sympathetic ophthalmia from other forms of uveitis.
**Why Each Wrong Option is Incorrect**
* **Option A:** This option is likely incorrect because it does not accurately describe the histopathological findings associated with sympathetic ophthalmia.
* **Option B:** This option may be incorrect because it does not specifically mention the Dalen-Fuchs nodule, which is a key diagnostic feature of sympathetic ophthalmia.
* **Option D:** This option is likely incorrect because it does not accurately describe the underlying pathophysiology of sympathetic ophthalmia.
**Clinical Pearl / High-Yield Fact**
Sympathetic ophthalmia is a rare but serious condition that can lead to severe vision loss if not promptly treated. It is essential for ophthalmologists and primary care physicians to be aware of this condition and its characteristic histopathological findings, including the Dalen-Fuchs nodule.
**Correct Answer:** C. Sympathetic ophthalmia.