Hi, thanks for your query. From your description of a flat lesion, not changing in size, no associated symptom and appearance of another one close to it, it seems that your partner has developed warts. Warts are due to a viral infection and are contagious. They can be easily treated by minimally invasive procedure like electro or radio cautery in a clinical setting. Other thing may be seborrhoeic keratosis or even a carcinomatous growth. You may consult a dermatologist for exact diagnosis and treatment. A skin biopsy may be done if diagnosis is clinically difficult. Hope this helps you. You may write back if you have any doubts.