What is the organ most commonly involved in graft-versus-host (GVH) reaction?

Skin is the Most Commonly Involved Organ in Graft-Versus-Host Reaction

The skin is the most commonly involved organ in graft-versus-host reaction (d). According to the National Comprehensive Cancer Network (NCCN) guidelines, skin is the primary target organ affected by graft-versus-host disease (GVHD), with significantly higher response rates to treatment compared to other organ systems 1.

Organ Involvement in GVHD

Primary Target Organs:

• Skin (most common):
  • Shows highest response rates to treatments (61-100% depending on therapy) 1
  • First organ typically affected in acute GVHD 2
  • Presents with rash/dermatitis, often as initial manifestation 2

Secondary Target Organs:

• Gastrointestinal tract:
  • 33% involvement in chronic GVHD 1
  • Presents with abdominal pain/diarrhea 2
• Liver:
  • Presents with hepatitis/jaundice 2
  • Lower response rates to treatments (25-36%) compared to skin 1
• Mouth:
  • 86% involvement in chronic GVHD 1

Evidence Supporting Skin as Primary Target

Multiple studies confirm skin as the predominant target:

1. Response to therapy data: Patients with skin GVHD were more likely to respond to ATG treatment, with 61% experiencing complete or partial response compared to only 27% without skin involvement (p=0.02) 1.

2. Organ involvement statistics: In chronic GVHD, skin involvement was documented in 81% of patients, compared to GI tract (33%) and other organs 1.

3. Treatment efficacy patterns: Treatments like rituximab show higher efficacy in skin GVHD (60% response rate) compared to oral mucosal (36%), liver (29%), and lung GVHD (30%) 1.

4. Pathophysiology: The skin has a unique immune microenvironment that makes it particularly susceptible to GVHD, with distinct mechanisms of injury compared to other target organs 3.

Clinical Presentations of Cutaneous GVHD

Skin manifestations of GVHD are diverse:

• Acute GVHD: Typically presents as blanchable, erythematous macular eruption 4
• Chronic GVHD: Can mimic various dermatological conditions:
  • Scleroderma-like changes 5
  • Lichen planus-like lesions 6
  • Lupus erythematosus-like butterfly rash 6
  • Eosinophilic fasciitis-like presentation 5

Diagnostic Considerations

Skin involvement in GVHD is diagnosed through:

• Clinical presentation of characteristic rash
• Skin biopsy showing typical histopathological features
• Exclusion of mimicking conditions (viral infections, drug reactions) 2

Treatment Implications

The high prevalence of skin involvement has important treatment implications:

• Skin-directed therapies are often first-line approaches
• Systemic treatments like ibrutinib show efficacy in 71% of skin GVHD cases 1
• Hydroxychloroquine is particularly effective for skin or oral involvement 1

Conclusion

Based on the comprehensive evidence from NCCN guidelines and supporting research, skin is definitively the most commonly involved organ in graft-versus-host reaction, with higher prevalence and better treatment response rates compared to other organ systems.