Wrist Extensor Tendinopathy: This condition is often associated with activities that involve repetitive wrist extension, such as pushups. The pain is typically localized to the dorsal aspect of the wrist and can be exacerbated by activities that involve gripping or extending the wrist.

Wrist Ganglion Cyst: A common cause of dorsal wrist pain, ganglion cysts are benign lumps that can cause discomfort, especially if they compress nearby nerves or tendons.
Scapholunate Ligament Sprain: This injury can occur from a fall onto an outstretched hand or from repetitive strain, such as pushups, leading to pain on the dorsal aspect of the wrist.
Intersection Syndrome: This condition involves inflammation of the tendons on the dorsal aspect of the wrist, where the extensor tendons of the thumb cross over the wrist extensor tendons, and can be exacerbated by activities like pushups.

Fracture (e.g., Scaphoid Fracture): Although less likely if the pain started with pushups and not a specific traumatic event, it's crucial to rule out fractures, as they can have serious consequences if left untreated.
Infectious Tenosynovitis: An infection within the tendon sheath, which can be a medical emergency requiring prompt treatment to prevent serious complications.
Gout or Pseudogout: These conditions can cause sudden, severe pain and swelling in the wrist and must be considered, especially if there's a history of similar episodes or risk factors.

Kienbock's Disease: A rare condition involving the collapse of the lunate bone in the wrist, which can cause chronic wrist pain.
Tumor (e.g., Giant Cell Tumor of Tendon Sheath): Although rare, tumors should be considered in the differential diagnosis of persistent, unexplained wrist pain.
Rheumatologic Conditions (e.g., Rheumatoid Arthritis): While less common as a cause of isolated dorsal wrist pain, these conditions can cause a wide range of symptoms, including wrist pain, and should be considered, especially if there are other systemic symptoms.