Seborrheic dermatitis (L21) ICD-10-CM
The L21 code range covers seborrheic dermatitis with 5 ICD-10-CM diagnosis codes. 4 of them are billable and valid for claim submission in fiscal year 2026, and the category headers group them but cannot themselves be billed.
Type 2 Excludes
A type 2 excludes note represents "Not included here". An excludes2 note indicates that the condition excluded is not part of the condition represented by the code, but a patient may have both conditions at the same time. When an Excludes2 note appears under a code, it is acceptable to use both the code and the excluded code together, when appropriate.
Codes in the L21 Range 5 codes · 4 billable
Clinical Terms in This Code Range
Definitions from the National Library of Medicine for conditions coded in the L21 range.
Parakeratosis
Persistence of the nuclei of the keratinocytes into the stratum corneum of the skin. This is a normal state only in the epithelium of true mucous membranes in the mouth and vagina. (Dorland, 27th ed)
Parapsoriasis
The term applied to a group of relatively uncommon inflammatory, maculopapular, scaly eruptions of unknown etiology and resistant to conventional treatment. Eruptions are both psoriatic and lichenoid in appearance, but the diseases are distinct from psoriasis, lichen planus, or other recognized dermatoses. Proposed nomenclature divides parapsoriasis into two distinct subgroups, PITYRIASIS LICHENOIDES and parapsoriasis en plaques (small- and large-plaque parapsoriasis).
Pityriasis
A name originally applied to a group of skin diseases characterized by the formation of fine, branny scales, but now used only with a modifier. (Dorland, 27th ed)
Pityriasis Lichenoides
A subgroup of PARAPSORIASIS itself divided into acute and chronic forms. The acute form is characterized by the abrupt onset of a generalized, reddish-brown, maculopapular eruption. Lesions may be vesicular, hemorrhagic, crusted, or necrotic. Histologically the disease is characterized by epidermal necrolysis. The chronic form shows milder skin changes with necrosis.
Pityriasis Rosea
A mild exanthematous inflammation of unknown etiology. It is characterized by the presence of salmon-colored maculopapular lesions. The most striking feature is the arrangement of the lesions such that the long axis is parallel to the lines of cleavage. The eruptions are usually generalized, affecting chiefly the trunk, and the course is often self-limiting.
Pityriasis Rubra Pilaris
A chronic skin disease characterized by small follicular papules, disseminated reddish-brown scaly patches, and often, palmoplantar hyperkeratosis. The papules are about the size of a pin and topped by a horny plug.
Tinea Versicolor
A common chronic, noninflammatory and usually symptomless disorder, characterized by the occurrence of multiple macular patches of all sizes and shapes, and varying in pigmentation from fawn-colored to brown. It is seen most frequently in hot, humid, tropical regions and is mostly caused by MALASSEZIA FURFUR (formerly Pityrosporum orbiculare).
About the L21 Code Range
ICD-10 code L21 covers seborrheic dermatitis, a common inflammatory skin condition affecting areas with many oil glands, such as the scalp and face.
These codes include specific types like L21.0 (Seborrhea capitis), commonly known as cradle cap or pityriasis capitis, which refers to seborrheic dermatitis localized to the scalp. L21.1 relates to seborrheic infantile dermatitis and encompasses varied presentations including seborrhea corporis and seborrheic eczema-like eruptions often seen in infants. L21.8 represents other seborrheic dermatitis forms such as flexural or erythrodermic types, and L21.9 is used when the condition is unspecified, including cases linked to human immunodeficiency virus infection. Understanding these distinctions in the ICD-10 code for seborrheic dermatitis aids healthcare professionals and coders in accurately categorizing the condition by specific affected areas and clinical features, improving documentation and treatment focus.
Questions About This Page
How many billable codes are in the L21 range?
Of the 5 codes in this range, 4 are billable and valid for claim submission from October 1, 2025 through September 30, 2026. Category header codes group them but cannot be reported on claims.
What does the L21 range classify?
The range classifies seborrheic dermatitis. Each code links to its own reference page with billing status, MS-DRG grouping, coding notes, and clinical information.
Related References
Source: CMS FY 2026 ICD-10-CM Tabular List and order file, effective October 1, 2025 through September 30, 2026.
