The M65.4 Diagnosis Code, as defined within the International Classification of Diseases, 10th Revision, Clinical Modification (ICD-10-CM), is a billable code used to specify the diagnosis of Radial styloid tenosynovitis, commonly known as De Quervain’s tenosynovitis. This article provides a comprehensive overview of the M65.4 code, its clinical context, and its significance in medical diagnosis and billing.
What is the M65.4 ICD-10-CM Code?
M65.4 is a specific and billable diagnosis code in the ICD-10-CM system. This means it is recognized for reimbursement purposes and is used by healthcare professionals and medical coders to accurately classify and document patient diagnoses. The 2025 edition of ICD-10-CM, which includes code M65.4, became effective on October 1, 2024, highlighting its current relevance in medical coding. It’s important to note that while M65.4 is the American ICD-10-CM version, international versions of ICD-10 M65.4 might have variations.
An illustration depicting the anatomical location of radial styloid tenosynovitis, commonly diagnosed using the M65.4 code.
De Quervain’s Tenosynovitis: Clinical Insights
De Quervain’s tenosynovitis, the condition represented by the m65.4 diagnosis code, is a stenosing tenosynovitis affecting specific tendons in the wrist. Specifically, it involves the abductor pollicis longus (APL) and extensor pollicis brevis (EPB) tendons located in the first dorsal wrist compartment. This condition is characterized by pain and tenderness at the radial styloid process, a bony prominence on the thumb side of the wrist.
Several approximate synonyms are used interchangeably with m65.4 diagnosis code and De Quervain’s tenosynovitis, including:
- Radial styloid tenosynovitis
- Tendonitis, De Quervain’s
- Tenosynovitis of the radial styloid (and specified as bilateral, left, or right when necessary)
Clinically, De Quervain’s tenosynovitis is frequently linked to overuse injuries, where repetitive hand or wrist movements contribute to tendon irritation and inflammation. It is also observed in association with rheumatoid arthritis, indicating an inflammatory component in some cases. The primary symptoms patients present with are pain when moving the thumb and wrist, especially with gripping or twisting motions. Diagnosis is often clinical, based on physical examination findings such as the Finkelstein test, which elicits pain when the thumb is flexed into the palm and the wrist is ulnarly deviated.
Related ICD-10-CM Codes and Context
Understanding the m65.4 diagnosis code also involves recognizing its place within the broader ICD-10-CM coding system. It falls under the category of synovitis and tenosynovitis (M65) and is positioned amongst other related conditions. Codes adjacent to M65.4 include those for trigger finger (M65.3) affecting different fingers and more general codes for other synovitis and tenosynovitis (M65.8) at various body sites. This contextual placement aids in accurate diagnosis coding and ensures specificity in medical records and billing.
For reimbursement and claims with service dates on or after October 1, 2015, the ICD-10-CM codes, including m65.4, are mandatory. This underscores the importance of using the correct and most current ICD-10-CM codes for accurate medical billing and record-keeping.
In conclusion, the m65.4 diagnosis code is a critical identifier for De Quervain’s tenosynovitis, a common and often debilitating condition affecting the wrist and thumb. Accurate use of this code is essential for proper diagnosis documentation, treatment planning, and healthcare administration.
