Skin lesions in immunosuppressed cancer patients have a broad differential of infectious and non-infectious causes. Rash may be an early indication of serious systemic infections that are otherwise difficult to diagnose; hence, skin biopsy with culture and histopathology plays a vital role in establishing a diagnosis. Our study aims to determine the yield of skin biopsy in identifying infections and its impact on diagnosis and therapy.
We performed a retrospective review of all cancer patients admitted to University of Maryland from August 2010 to October 2017 who had a skin biopsy for new rash. We classified the skin lesion as infectious if the biopsy pathology or culture showed a pathogenic organism.
Of 269 patients biopsied for new skin lesions, 43 (16%) were caused by infection and 226 (84%) were non-infectious. Among non-infectious causes, 63% were due to graft vs. host disease, 9% cancer, 9% drug reaction, 4% Sweet syndrome, and 29% were non-diagnostic. The median WBC count trended toward significantly lower in the infectious group (1100/mcL) vs. the non-infectious group (2700/mcL; p=0.08).
Of the 43 infectious lesions, 21 (49%) were fungal, 13 (30%) bacterial, 7 (16%) viral and 1 (2%) mycobacterial. 67% patients had absolute neutrophil counts <1000/mcL, 40% were febrile, and 28% had had a stem cell transplant. The majority of infections (58%) were identified by skin biopsy alone.
Change in diagnosis after biopsy was significantly more likely in patients with infectious cause of skin lesions than non-infectious (47% vs. 28%, respectively, p<0.02). Patients with a biopsy-confirmed infectious cause were 5 times (95% CI 2.70-10.22) more likely to have a change in therapy post biopsy compared to patients with a non-infectious cause. The sensitivity and specificity of provider diagnosis prior to biopsy was 86% and 81%, respectively. The positive predictive value of pre-biopsy provider diagnosis was low at 46%.
Skin biopsy of new rash in immunocompromised cancer patients frequently reveals systemic infections (especially fungal) and often leads to a change in diagnosis and therapeutic management.
D. J. Riedel, None
See more of: Poster Abstract Session