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Invasive Cutaneous Mucormycosis in a Patient With Chronic Lymphocytic Leukemia on Obinutuzumab, Idelalisib, and Bruton Tyrosine Kinase Degrader: A Case Report

Summary

A 74-year-old man with blood cancer developed a serious fungal skin infection caused by Mucorales while taking multiple targeted cancer drugs. The infection appeared as a darkening ulcer on his ankle that rapidly worsened. Doctors diagnosed it using a skin biopsy showing characteristic fungal structures, though standard fungal tests came back negative. The patient required amputation of his leg below the knee to remove all the infected tissue, along with antifungal medications, and ultimately recovered.

Background

Invasive fungal infections due to Mucorales are significant infectious complications in patients with hematologic malignancy with high mortality rates. New targeted biologic therapies have expanded treatment options but variable effects on innate and humoral immunity creating additional IFI risk. Early diagnosis and treatment of invasive mucormycosis remains challenging.

Objective

To present a case of invasive cutaneous mucormycosis in a patient with chronic lymphocytic leukemia receiving multiple targeted biologic therapies and discuss diagnostic approaches and treatment strategies.

Results

Histopathology revealed broad aseptate fungal hyphae with angioinvasion pathognomonic for cutaneous mucormycosis despite negative fungal cultures and NGS. Extensive necrosis required limb amputation below the knee for source control. Patient achieved clinical cure with liposomal amphotericin B, followed by isavuconazole after surgery, with clear surgical margins confirmed.

Conclusion

This is the first reported case of invasive cutaneous mucormycosis in a CLL patient on newer targeted biologics including BTK degrader, obinutuzumab, and idelalisib. Histopathology was essential for timely diagnosis given limitations of culture and molecular testing. Early diagnosis and aggressive surgical source control achieved clinical cure and emphasizes need for high clinical suspicion in immunocompromised patients.
  • Published in:Cureus,
  • Study Type:Case Report,
  • Source: PMID: 41133038, DOI: 10.7759/cureus.92967
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