Milker's Nodules Clinical Presentation
- Author: Justin J Finch, MD, FAAD; Chief Editor: William D James, MD more...
Patients typically have no previous history of milker's nodule. Patients with milker's nodules have had recent contact with infected cows, calves, or viral fomites. (Milker's nodules are contracted from cows; orf nodules are contracted from sheep or goats.) The incubation period for milker's nodules may be as brief as 4 days or as long as several weeks.
Lesions of milker's nodules are often solitary, and they may be pruritic or painful. Some authorities divide the clinical course of milker's nodules into 6 stages, each lasting roughly 1 week, as follows:
Target (a papulovesicular lesion with a red center, white ring, and red periphery)
Acute weeping nodule (characterized by loss of epidermis over the center)
Dry, crusted nodular
Lesions of milker's nodules are usually found on the fingers, the hands, and the forearms and are nearly identical to those seen in orf. Usually, only a few or even a single lesion is present. Occasionally, many lesions are distributed in a larger area, such as a burn site.[6, 7]
Classic milker's nodules lesions are 0.5-1.5 cm in diameter, firm, movable, dome-shaped papules or nodules. Milker's nodules may be red or purplish red in color, or they may have a targetlike appearance. Central ulceration or crust may occur. Lesions typically have a grayish coating in the target stage and a verrucous surface in the papillomatous stage.
Milker's nodules often present with a vascular appearance resembling pyogenic granuloma. Milker's nodules are on average smaller than orf lesions, but they may not be distinguishable on a clinical basis. Variant lesions may include vesicles, scaly patches, and erosions. (The patient's history guides the differential diagnosis in these cases.) Local lymphadenopathy may be present.
A focused physical examination should be performed. The following findings have been described in patients with milker's nodules:
Milker's nodules are caused by a double-stranded DNA virus of the genus Parapoxvirus. Milker's nodule is a zoonosis endemic to and common in cattle worldwide.
Human milker's nodules are contracted through direct transmission (ie, handling of infected cow teats, calf muzzles, other sites of active bovine infection) or through indirect transmission (ie, handling of virally contaminated objects).
Evidence suggests that milker's nodule virus (traditionally associated with disease contracted from papulonodular lesions on cow teats) and bovine papular stomatitis virus (traditionally isolated from erosive lesions on calf muzzles) may be different though closely related viruses. It seems that they may both cause milker's nodule in humans. In fact, each may cause both types of lesions in cattle.
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