C96.6 — Unifocal Langerhans-cell histiocytosis

BillableCC

Is C96.6 billable?

Yes — C96.6 is billable for FY2027. C96.6 is a valid, billable ICD-10-CM code at the highest level of specificity in its branch. C96.6 may be submitted for encounters from October 1, 2026 through September 30, 2027.

C96.6 at a glance

Code	C96.6
Description	Unifocal Langerhans-cell histiocytosis
Billable	Yes
Code set	ICD-10-CM FY2027
Valid for encounters	October 1, 2026 – September 30, 2027

Which MS-DRGs does C96.6 group to?

C96.6 sits in MDC 10 and helps define the logic of 1 MS-DRG (version 44, FY2027). Which one a stay actually groups to also depends on procedures and secondary diagnoses.

642Inborn and Other Disorders of Metabolismmedical

As a secondary diagnosis, C96.6 is a complication or comorbidity (CC), which can move a stay into a higher-paying DRG.

How is C96.6 listed in the Alphabetic Index?

These are the routes through the Alphabetic Index that lead to C96.6. They show the wording a clinician may have documented, which often differs from the Tabular description.

Granuloma › eosinophilic
Histiocytosis › Langerhans' cell NEC
Histiocytosis › X NEC
Granuloma › bone › eosinophilic
Granuloma › bone › lung
Granuloma › eosinophilic › bone
Granuloma › eosinophilic › lung
Granuloma › lung › eosinophilic
Histiocytosis › Langerhans' cell NEC › unifocal
Histiocytosis › mononuclear phagocytes NEC › Langerhans' cells
Histiocytosis › X NEC › chronic
Histiocytosis › X NEC › unifocal

Excludes1 — never code together

The conditions below can never be reported together with C96.6 on the same claim. An Excludes1 note means the two conditions cannot occur in the same patient, so reporting both is a coding error.

multifocal and multisysemic (disseminated) Langerhans-cell histiocytosis (C96.0)
multifocal and unisystemic Langerhans-cell histiocytosis (C96.5)

Inclusion terms

Alternative wording in documentation that is classified to C96.6.

Eosinophilic granuloma
Histiocytosis X, unifocal
Histiocytosis X NOS
Langerhans-cell histiocytosis NOS

Excludes1 — never code together — inherited from C96

The conditions below can never be reported together with C96.6 on the same claim. An Excludes1 note means the two conditions cannot occur in the same patient, so reporting both is a coding error.

personal history of other malignant neoplasms of lymphoid, hematopoietic and related tissues (Z85.79)

Excludes2 — not included here — inherited from C81-C96

The conditions below are not part of C96.6, but a patient may have both at the same time. When documentation supports it, C96.6 and the excluded code may both be reported.

Kaposi's sarcoma of lymph nodes (C46.3)
secondary and unspecified neoplasm of lymph nodes (C77.-)
secondary neoplasm of bone marrow (C79.52)
secondary neoplasm of spleen (C78.89)

How long has C96.6 existed?

C96.6 has been in ICD-10-CM since at least FY2016, the earliest fiscal year on record here.

Derived from the official order files for FY2016–FY2026. FY2017 and FY2020 publish no order file, so those years are not covered.

Which codes are confused with C96.6?

ICD-10-CM declares these codes mutually exclusive with C96.6 — exactly one of each pair can be correct for a given encounter.