L04.9 Acute lymphadenitis, unspecified

Billable ICD-10-CM code, FY2026.

Applies from L04 Acute lymphadenitis

Includes

• abscess (acute) of lymph nodes, except mesenteric
• acute lymphadenitis, except mesenteric

Excludes1 (never code together)

• chronic or subacute lymphadenitis, except mesenteric (I88.1)
• enlarged lymph nodes (R59.-)
• human immunodeficiency virus [HIV] disease resulting in generalized lymphadenopathy (B20)
• lymphadenitis NOS (I88.9)
• nonspecific mesenteric lymphadenitis (I88.0)

MS-DRG index

Defines the logic of DRG(s) 791 in MDC 15.

Approximate ICD-9-CM (GEMs)

• 683 Acute lymphadenitis (approximate)

Code annotations containing back-references to L04.9

Back-references to L04

• Type 2 Excludes: D75 Other and unspecified diseases of blood and blood-forming organs ("acute lymphadenitis (L04.-)")
• Type 1 Excludes: I88 Nonspecific lymphadenitis ("acute lymphadenitis, except mesenteric (L04.-)")
• Type 2 Excludes: L89 Pressure ulcer ("skin infections (L00-L08)")
• Type 2 Excludes: L97 Non-pressure chronic ulcer of lower limb, not elsewhere classified ("skin infections (L00-L08)")
• Type 2 Excludes: L98.4 Non-pressure chronic ulcer of skin, not elsewhere classified ("skin infections (L00-L08)")
• Type 2 Excludes: L98.A Non-pressure chronic ulcer of upper limb, not elsewhere classified ("skin infections (L00-L08)")
• Type 1 Excludes: R59 Enlarged lymph nodes ("acute lymphadenitis (L04.-)")

Diagnosis Index entries for L04.9

• Adenitis › acute, unspecified site
• Adenitis › gangrenous
• Lymphadenitis › acute

Nearby codes

• L04.0 Acute lymphadenitis of face, head and neck
• L04.1 Acute lymphadenitis of trunk
• L04.2 Acute lymphadenitis of upper limb
• L04.3 Acute lymphadenitis of lower limb
• L04.8 Acute lymphadenitis of other sites
• L04.9 Acute lymphadenitis, unspecified (this code)