Morbilliform Eruptions After Stem Cell Transplant: Differential Diagnosis and Management

Conclusions

• After stem cell transplant, morbilliform eruptions require careful clinical correlation because drug eruption, viral exanthem, acute GVHD, engraftment syndrome, and lymphocyte recovery eruptions can look very similar.
• In allogeneic transplant recipients, acute cutaneous GVHD is a leading concern and is suggested by folliculocentric rash, acral involvement such as palms, soles, ears, and scalp, and concurrent GI or liver abnormalities.
• Time since transplant alone is not sufficient to diagnose GVHD, because modern classification relies more on morphology and systemic context than on a strict day-100 cutoff.
• Skin biopsy has limited value for distinguishing acute GVHD from drug eruption because histology is often nonspecific, so treatment should not be delayed when clinical suspicion is high.
• Facial involvement, especially with palms and soles, plus diarrhea and hyperbilirubinemia, strongly favors acute GVHD over morbilliform drug eruption.
• General GVHD risk is increased by HLA mismatch, unrelated donors, older donor or recipient age, female donor to male recipient, total body irradiation, donor lymphocyte infusion, and tapering immunosuppression.
• Newer conditioning regimens may reduce the overall incidence of acute GVHD.
• Acute GVHD is treated first with systemic steroids when extensive or systemic, while skin-limited disease may be managed with topical steroids, calcineurin inhibitors, phototherapy, or topical ruxolitinib.
• For steroid-refractory acute GVHD, ruxolitinib and other institution-dependent systemic therapies or extracorporeal photopheresis may be used.
• In autologous transplant recipients, acute GVHD is uncommon, and engraftment syndrome is often a more likely explanation for fever, rash, edema, and pulmonary infiltrates around neutrophil recovery.
• Engraftment syndrome is characterized by noninfectious fever, morbilliform rash, and edema or pulmonary edema during ANC recovery, and it is usually responsive to systemic steroids.
• Cutaneous eruption of lymphocyte recovery is a self-limited morbilliform eruption that occurs 1 to 3 weeks after chemotherapy during lymphocyte recovery and usually lacks significant systemic involvement.