Others theorised that Her Majesty may have dropped something on it or otherwise injured her hand, but doctors have suggested the bruising may be caused by something else.
"A lack of circulation, frail skin, exposed veins, bruising, a leakage of blood to the tissue beneath the skin causing the colour," GP Giuseppe Aragona told The Express.
"It could be cyanosis which occurs when there is not enough oxygen in the blood… this could be linked to her recent injury."
The Queen has faced a slew of health issues since late 2021, when she was hospitalized overnight in October, then suffered a back sprain and battled COVID-19 in early 2022.
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More recently the monarch has been dealing with mobility issues which have prevented her from attending some major events, including the royal Easter service, and had her relying on a walking stick for others.
The 96-year-old has also limited herself to attending shorter engagements, a change made for her comfort according to Buckingham Palace.
While the bruise on her hand is just the latest in a string of concerning health updates, it’s not the first time Her Majesty has been spotted with such an injury.
Royal fans spotted a similar blemish on the back of her hands in 2019 during a meeting with the Jordanian royals in Windsor, which was theorized to be due to poor circulation.