C96.0

HCC Category Mapping

What This Code Means

A rare cancer involving abnormal growth of Langerhans cells (immune cells) that affects multiple sites throughout the body.

Coding Tips

• •This code indicates disseminated/multisystemic disease; confirm multiple organ involvement is documented
• •Distinguish from C96.6 (unifocal) which affects only one site

Clinical Significance

Multifocal and multisystemic Langerhans-cell histiocytosis (historically called Letterer-Siwe disease) is a systemic disorder involving abnormal proliferation of Langerhans cells affecting multiple organs including bone, skin, liver, spleen, and lungs. It primarily affects young children and carries significant morbidity and mortality when organs such as the liver, spleen, or hematopoietic system are involved.

Documentation Requirements

• ✓Documentation must confirm the multisystemic nature with at least two organ systems involved, supported by biopsy demonstrating CD1a-positive or CD207-positive Langerhans cells.
• ✓The specific organs involved, extent of disease, risk stratification (high-risk vs.
• ✓low-risk based on organ involvement), and treatment response should be documented.

Commonly Confused Codes