The patient has temporal arteritis. Glucocorticoids cause neutrophilia by demarginating neutrophils adhered to the vascular endothelium and stimulating the bone marrow to release neutrophils.
Patients treated with glucocorticoids may experience leukocytosis and neutrophilia. Notably on a differential, eosinophils and lymphocytes are often decreased. Exogenous and endogenous glucocorticoids (in the form of stress hormones) may cause neutrophilia. Examples of patients who may experience neutrophilia from endogenous stress hormones alone are patients with seizures, surgical patients, and even patients who have experienced emotional stress. One should also know the long term effects of steroids which include suppression of ACTH (and adrenal insufficiency if abruptly discontinued), iatrogenic Cushing's syndrome, osteoporosis, hyperglycemia, gastric ulceration, sodium retention, hypertension, decreased wound healing, increased infections, and cataracts.
Abramson and Melton discuss the basics of clinical assessment of leukocytosis. In clinical practice, the most common cause is infection or inflammatory processes caused by benign conditions. Less commonly, the finding results from a primary bone marrow disorder. A normal bone marrow reaction to infection or inflammation is an increase in white blood cells, predominantly neutrophils, resulting in a left shift. Medications commonly associated with leukocytosis include corticosteroids, lithium and beta agonists.
Ness et al. discuss the diagnosis and treatment of giant cell arteritis. This disease is the most common systemic vasculitis in people aged 50 and above. Typical symptoms include bitemporal headache, scalp tenderness, jaw claudication, visual disturbances, fever, weight loss, and polymyalgia. The standard treatment is with corticosteroids.
Figure A shows the classic ischemic appearance of the nerve in temporal arteritis. Illlustration A depicts the therapeutic and the adverse effects of treatment with glucocorticoids.
Answer 1: Bacterial infection could result in a neutrophilic leukocytosis, but drug effect is more likely in this case.
Answer 2: Malignancy usually results in a more chronic and profound leukocytosis.
Answer 3: Lab error is unlikely given this patient has a good reason to have leukocytosis.
Answer 5: A viral infection would result in a lymphocytosis, not neutrophilia.
Abramson N1, Melton B. Leukocytosis: basics of clinical assessment. Am Fam Physician. 2000 Nov 1;62(9):2053-60.
PMID:11087187 (Link to Abstract)
Ness T1, Bley TA, Schmidt WA, Lamprecht P.The diagnosis and treatment of giant cell arteritis.Dtsch Arztebl Int. 2013 May;110(21):376-85; quiz 386. doi: 10.3238/arztebl.2013.0376. Epub 2013 May 24.
PMID: 23795218 (Link to Abstract)