The old hospital was closed in 1910, so the painting is probably older than that. Carl Mathorne portrayed professor (and chief surgeon at the hospital) Oscar Wanscher in 1906, which might give a clue to the date.
<bdi><a href="https://www.wikidata.org/wiki/Q61995921" class="extiw" title="d:Q61995921"><span title="Danish painter (1878-1942)">Carl Mathorne</span></a>
</bdi>
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