Coding Rules Current as at 18-Oct-2016 08: 31

Published 15 June 2015,
for implementation 01 July 2015.

Ref No: Q2873 | Published On: 15-Jun-2015 | Status: Current

SUBJECT: IgG4-related disease

Q:

How do you code immunoglobulin G4-related disease?

A:

Immunoglobulin G4-related disease (IgG4-related disease) (IgG4-RD) is synonymously known as:

1. 
   IgG4-related systemic disease or IgG4-related sclerosing disease (IgG4-RSD)
   
2. 
   IgG4-related autoimmune disease
   
3. 
   IgG4-related multiorgan lymphoproliferative syndrome (IgG4-MOLPS)
   
4. 
   IgG4-associated multifocal systemic fibrosis
   
5. 
   systemic IgG4 plasmacytic syndrome (SIPS)
   

IgG4-RD is a fibroinflammatory condition characterised by elevated levels of IgG4-positive plasma cells in affected organ tissue, with fibrosis and with or without elevated serum IgG4 concentrations. Elevated serum IgG4 concentrations were first recognised in patients with autoimmune pancreatitis; manifestations outside of the pancreas were later identified and the condition was recognised as a systemic condition in 2003.

IgG4-RD may manifest in the; pancreas, hepatobiliary tract, salivary glands, periorbital tissues, kidneys, lungs, lymph nodes, meninges, aorta, breast, prostate, thyroid, pericardium, retroperitoneum and skin. Many conditions that were previously considered to be confined to single organs are now recognised as part of the spectrum of IgG4-RD, for example, Mikulicz’s syndrome, Riedels’ thyroiditis and retroperitoneal fibrosis. Symptoms of IgG4-RD are dependent upon the organ in which it manifests. There may be organ swelling (due to the presence of a fibrotic mass), damage or failure of the target organ. For example, patients may present with urinary symptoms due to obstruction of the ureter(s) from extensive retroperitoneal fibrosis.

Diagnosis of IgG4-RD includes histopathological identification of the presence of extensive numbers of IgG4-positive plasma cells in the affected tissue. Elevated serum IgG4 concentrations are suggestive but not a definitive diagnosis of IgG4-RD. Treatment includes administration of glucocorticoids, but immunosuppressive or B-cell depleting therapy may also be required.

The classification of IgG4-related disease is currently being considered internationally.

In the interim, assign the following code for IgG4-related disease (and all synonymous terms):

D89.8 Other specified disorders involving the immune mechanism, not elsewhere classified

by following the index pathway:

Disorder

- immune mechanism

- - specified type NEC D89.8

Also assign codes for specific manifestations (for example, retroperitoneal fibrosis), with sequencing as per the guidelines in ACS 0001 Principal diagnosis and ACS 0002 Additional diagnoses.

(See also Coding Rules: Retroperitoneal fibrosis).

References:

Guma, M., and Firestein, G. (2012). IgG4-related diseases. Best Practice and Research Clinical Rheumatology. Volume 26, Issue 4, August 2012, pages 425-438. doi:10.1016/j.berh.2012.07.001

Khosroshahi, A., and Stone, J. (2011). A clinical overview of IgG4-related systemic disease. Current Opinion in Rheumatology. Volume 23(1), January 2011, p57-66. doi 10.1097/BOR.0b013e3283418057

Stone, J., Zen, Y., and Deshpande, V. (2012). IgG4-related disease. The New England Journal of Medicine 2012; 366:539-551. February 9, 2012 doi: 10.1056/NEJMra1104650