Final answer:
Flat-topped violaceous papules found on the knuckles and interphalangeal joints are characteristic of Dermatomyositis, a chronic inflammatory disease of muscles and skin.
Step-by-step explanation:
The skin condition described as flat-topped violaceous papules found on knuckles and interphalangeal joints is most likely indicative of Dermatomyositis. Dermatomyositis is a chronic inflammatory disease that affects the muscles and the skin, and one of its distinct skin manifestations includes the presence of violaceous, or purple, papules over the knuckles, known as Gottron's papules. These papules or eruptions are a hallmark feature of the condition and differ from the scaly plaques typically seen in psoriasis, the flat-topped papules of lichen planus, or the various skin manifestations associated with Systemic Lupus Erythematosus (SLE).