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Monday, January 31, 2011

USMLE question No. 1: A 67-year-old woman presents with a 4-week history of headaches, facial pain, blurred vision, and intense pain ...

A 67-year-old woman presents with a 4-week history of headaches, facial pain, blurred vision, and intense pain and stiffness in her shoulders and hips. She is diagnosed with a vasculitis, and a biopsy of an affected artery is taken. Histological examination is most likely to reveal which of the following characteristic findings?

(A) concentric “onion skin” thickening and fibrosis
(B) extensive intra- and extravascular granulomatous inflammation
(C) fragmentation of the internal elastic lamina with giant cells
(D) hyaline arteriolosclerosis and luminal narrowing
(E) segmental fibrinoid necrosis and neutrophil infiltration

Answer:
C:
The most likely diagnosis in this case isgiant cell (temporal) arteritis; it is both the most
common systemic vasculitis in this woman’s age group (>60) and is suggested by the clinical
history. Giant cell arteritis may affect any medium- and large-sized arteries, but principally
involves vessels in the head, that is, extracranial branches of the carotid arteries.
Vascular insufficiency leads to symptoms of jaw or facial pain, headaches, and visual
changes, as reported by this patient. In particular, ischemic optic neuropathy may occur
abruptly, resulting in permanent blindness; for this reason, patients with ocular disturbances in
suspected cases demand immediate medical intervention. Temporal arteritis has a strong,
well-known association with polymyalgia rheumatica, a systemic inflammatory disorder
causing symmetrical, often severe muscle pain and stiffness in the shoulders and pelvic girdle
(also reported by this patient); both conditions are associated with the HLA-D4 haplotype.
Microscopically, a section of a vessel affected by giant cell arteritis will demonstrate fragmentation of the internal elastic lamina and the presence of multinucleated giant cells.
Concentric “onion skin” thickening and fibrosis (choice A) may be seen most commonly in
malignant hypertension but also in other conditions such as primary sclerosing cholangitis.
Extensive intra- and extravascular granulomatous inflammation (choice B) refers to
Wegener granulomatosis which often includes:
(i) acute necrotizing granulomas of the upper
and/or lower respiratory tract;
(ii) granulomatous
vasculitis; and
(iii) renal disease.

Hyaline arteriolosclerosis and luminal narrowing (choice C) is found in association with benign hypertension and in diabetes mellitus but is also seen in some normotensive, nondiabetic elderly individuals. Segmental fibrinoid necrosis and neutrophil infiltration (choice E) is a description of the acute phase of polyarteritis nodosa.

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