Introduction
This topic covers skin infections acquired at work from biological agents carried by animals, plants, soil and damp environments. The five conditions to know are milkers' nodule, erysipeloid of Rosenbach, cutaneous actinomycosis, occupational paronychia (Candida) and occupational trichophytosis. For each, the oral answer should give the agent and route of entry, the typical lesion and course, how the diagnosis is confirmed, how it is separated from other conditions, and how exposure is controlled.
General principles and comparison
Occupational skin infections develop when a biological agent enters through skin that has been broken or macerated by work. The exposure history is the core of the diagnosis: occupation, task, animal or plant species, wounds, and wet work. The table compares the five conditions.
Milkers' nodule
Milkers' nodule is a benign viral infection passed from cattle to people who handle them, such as dairy workers, farmers and veterinarians. Infection follows contact with the teats and udder.
- Lesion: one or a few firm, pink-red, dome-shaped nodules on the dorsum of the hand, wrist or forearm, usually painless or mildly tender.
- Course: the nodule resolves spontaneously in about 1 to 2 months and may leave transient hyperpigmentation.
- Diagnosis: clinical and occupational history; histology shows ballooning degeneration of keratinocytes with eosinophilic intracytoplasmic inclusions; PCR is available.
- Differential: pyogenic granuloma, verruca, squamous cell carcinoma, atypical mycobacterial infection.
- Treatment: no antibiotics needed; avoid scratching; excision only if the lesion persists or the diagnosis is doubtful; protective gloves.