A 74-year-old woman presents to the clinic with a 2-week history of severe, unilateral rig… — USMLE Step 3

A 74-year-old woman presents to the clinic with a 2-week history of severe, unilateral right-sided temporal headache and generalized fatigue. She also reports pain in her jaw muscles when chewing meat, which resolves shortly after she stops eating. Yesterday, she experienced a transient episode of vision loss in her right eye that lasted for 10 minutes before fully resolving. Her temperature is $37.8^\circ\text{C}$ ( $100.0^\circ\text{F}$ ). Physical examination reveals a tender, nodular, and non-pulsatile right temporal artery. Laboratory studies show an erythrocyte sedimentation rate (ESR) of $85\text{ mm/h}$ (normal: $<20\text{ mm/h}$ ). A biopsy of the symptomatic temporal artery is scheduled to confirm the diagnosis. Which of the following histopathologic findings are most likely to be present in this patient's biopsy specimen? (Select all that apply)

Multinucleated giant cells infiltrating the tunica mediaAnswer
B
Fibrinoid necrosis of the vessel wall with a dense neutrophilic infiltrate
Disruption and fragmentation of the internal elastic laminaAnswer
D
Transmural granulomatous inflammation with abundant eosinophils
E
Deposition of IgA immune complexes in the vascular wall

Answer

The correct findings are multinucleated giant cells infiltrating the tunica media AND disruption and fragmentation of the internal elastic lamina.

Giant Cell Arteritis (Temporal Arteritis) is a systemic granulomatous vasculitis that typically affects the branches of the carotid artery. The classic histopathologic features seen on a temporal artery biopsy include a transmural inflammatory infiltrate composed of lymphocytes and macrophages, the presence of multinucleated giant cells (often located near the fragmented elastic lamina), marked intimal thickening (which causes luminal narrowing and downstream ischemia like jaw claudication), and the fragmentation and disruption of the internal elastic lamina.

Step-by-Step Solution

Analyze the patient's clinical presentation and demographic profile.

The patient is an elderly female with new-onset temporal headache, jaw claudication, transient monocular vision loss (amaurosis fugax), and a significantly elevated ESR.

Identifying the classic symptom triad establishes the most likely clinical diagnosis before interpreting the expected biopsy results.

Formulate the most likely primary diagnosis based on the clinical syndrome.

The presentation is highly characteristic of Giant Cell Arteritis (Temporal Arteritis).

Jaw claudication and amaurosis fugax in an elderly patient with an elevated ESR are hallmark features of this large-vessel vasculitis.

Correlate the clinical diagnosis with its defining histopathologic features on arterial biopsy.

Giant Cell Arteritis features granulomatous inflammation of the media, intimal thickening, multinucleated giant cells, and fragmentation of the internal elastic lamina.

Diagnostic confirmation requires identifying the specific microscopic patterns that differentiate it from other forms of vasculitis.

Key Concept

Giant Cell Arteritis (Temporal Arteritis) Histopathology

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