The South African-born all-rounder was diagnosed with a brain tumour in the early part of last year, but the news was only made public in October. He had undergone surgery, chemotherapy and radiation treatment in a bid to fight the illness.
De Lange, who turned out for the Cape Cobras and Knights franchise teams in South Africa prior to a spell with Northamptonshire in English county cricket, played in 13 One Day Internationals (ODIs) and eight T20 internationals for Scotland, making his debut in 2015.
A popular character in the scotland dressing room, de Lange was appointed the team's vice-captain for the Desert T20 tournament in the UAE in January 2017. His finest moment for Scotland came in a victory over Zimbabwe in June 2017, taking five wickets for 60 in the team's first win against a full member of the ICC.
Shortly after the memorable win, de Lange began missing games during the World Cricket League championships in Dubai. His absence was put down to "severe migraine headaches" but further tests in Scotland revealed the more serious diagnosis. He played his last international match for Scotland - an ODI against Papua New Guinea - on November 25, 2017.
A statement from Cricket Scotland read: "It is with great sadness that Cricket Scotland shares the news that Con de Lange passed away on Thursday 18th April 2019.
"A great servant to Scotland and the game of cricket, our thoughts are with his family at this difficult time."
During his career de Lange took 183 first-class wickets, 149 in List A cricket and 33 in T20 matches, as well as more than 4,500 career runs across the game's three formats.
He is survived by wife Claire and children Daisy and Rory.
Former team-mates took to Twitter to express their sadness at de Lange's passing. Ex-Scotland cricketer Gordon Goudie wrote: "Devastated to wake to the news of Con de Lange passing away this morning... thoughts to all his family and friends."
Former Northants colleague Jack Brooks said: "Really sad news to hear former Northants teammate Con de Lange passed away over night. Fine cricketer, hero of a man, funny chap and all-round lovely guy. Hope his wife Claire and the kids get all the support they need."
Northants captain Alex Wakeley added: "Absolutley devastated to wake up to the news that former Northants champ and friend, Con de Lange has passed away. One of the greatest blokes you will ever meet. Never forgotten."
De Lange's former club Ferguslie posted a statement that read: "Desperately sad news as former club professional and Clydesdale club coach Con de Lange has passed away aged just 38 after his battle with illness. Our condolences go to Con's family and friends at this difficult time."
Grange Cricket Club, which hosted many of Scotland's home matches, issued a statement of their own: "Our heart and love goes out to the family and friends of Con de Lange. Not only a fantastic cricketer and coach, but a wonderful person too. Rest in peace Con."
Former South Africa captain Jacques Kallis wrote: "Sad to hear of the passing of Con De Lange. Thoughts and prayers go out to his friends and family. RIP."
Ireland T20 captain Gary Wilson added: "Thoughts with the family and friends of Con de Lange this morning as well as our friends at Cricket Scotland. Very sad news."