Day 5: Discharge
Over the next two days, the patient’s eruption begins to resolve with significant decreases in pain, erythema, and swelling. His vital signs continue to remain within normal limits. After a four-day inpatient stay, the patient is discharged on a regimen of Doxycycline 100 mg twice daily and prednisone 10 mg daily. He is counseled on methamphetamine cessation. He leaves in stable condition and is instructed to follow-up with infectious disease and his primary care physician in 2 weeks. HisBartonella henselae assay results are returned after discharge revealing negative serology for IgG and IgM, providing further evidence for the suspected diagnosis of IgAV.
DISCUSSION
An annular rash can manifest secondary to a wide variety of both cutaneous and systemic diseases. These same pathologies are often defined by intrinsic variability in presentation and progression, further complicating the diagnostic process. The patient described in this case report possessed numerous risk factors for systemic disease including illicit drug use, invasive dental procedures, and exposure to unvaccinated animals, necessitating a broad scope of clinical suspicion. The patient’s initial complaint of a rash secondary to cat scratches favored a diagnosis of Bartonella henselae infection. Also known as cat scratch disease, this infection most commonly presents as a cutaneous eruption with regional lymphadenopathy but can include fever, visceral organ involvement, and neurologic manifestations [2]. An erythematous, vesicular lesion develops at the site of inoculation, often where a young cat or cat with fleas has scratched a patient. In this case, the patient’s non-blanching lesions and exposure to unvaccinated kittens favored this diagnosis [3]. However, the absence of lymphadenopathy and fever warranted further exploration.
DRESS syndrome was proposed as an alternative diagnosis by the infectious disease team. This drug-induced hypersensitivity reaction often initially involves a maculopapular rash that coalesces to form purpura and/or annular lesions. Cutaneous findings are often accompanied by eosinophilia and leukocytosis, as well as systemic symptoms, such as fever, lymphadenopathy, and signs of visceral organ involvement [4]. The patient’s respiratory complaints, eosinophilia, and annular rash coincided with this description. Additionally, though DRESS syndrome is most often associated with antiepileptics, allopurinol, sulfonamides, and vancomycin, cases of clindamycin-induced DRESS have been reported [5, 6]. Though the patient’s recent medication use did coincide with the progression of this eruption, characteristics of DRESS still did not fully satisfy his clinical picture.
Throughout the patient’s extensive workup, IgAV (formerly Henoch-Schönlein purpura) persisted as a potential diagnosis despite its non-classical presentation. Often diagnosed in children between four and six years of age, only approximately 10% of cases of IgAV occur in adults [7]. This self-limited systemic vasculitis is characterized by palpable purpura, arthralgias, abdominal pain, and kidney dysfunction and shows a preponderance for males (male-to-female ratio of 1.5:1) [8]. While the pathogenesis of IgAV is not fully understood, symptoms are presumed to be secondary to IgA immune-complex deposition within the skin and viscera [9, 10]. Recent reports have also associated the onset of IgAV with COVID-19 and group A streptococcus infections [11, 12]. Laboratory studies in IgAV patients may show mild leukocytosis, elevated inflammatory markers (ESR and CRP), occasional eosinophilia, and normal platelet levels; however, definitive diagnosis is obtained via skin biopsy. Biopsy will reveal leukocytoclastic vasculitis with deposition of IgA and fibrinoid necrosis, occurring most commonly in small vessels [13].
In this case, the patient’s age and lack of hallmark symptoms—renal, gastrointestinal, and joint manifestations—caused clinicians to question IgAV as a diagnosis of the observed annular eruption. However, rash morphology, respiratory symptoms (which may have been induced by COVID-19 due to endemic spread at the time of presentation), eosinophilia, and positive inflammatory markers suggested otherwise. It was not until punch biopsy results were received that IgAV was elevated to the primary differential. Considered the gold-standard of IgAV diagnosis, punch biopsy findings of “fibrinoid necrosis with a leukocytic and neutrophilic infiltrate” prompted the addition of steroids to the patient’s treatment protocol, an intervention which was successful in reducing his symptomology. This case emphasizes the necessity of a comprehensive patient workup including extensive history, physical, and laboratory evaluation. Additionally, the patient’s presentation, suggestive in-part of numerous pathologies, encourages clinicians to maintain a broad differential and exercise awareness of non-classical presentations. Such approaches can prevent the premature disregard of disease states for which the patient does not satisfy all traditional criteria and allow for a prompt improvement in patient health.
CONCLUSION
Proper diagnosis and treatment of annular rashes can prove challenging due to tremendous variety in pathologic associations. When evaluating these eruptions, it is essential to remain cognizant of atypical presentations of disease and to conduct a thorough history, physical, and laboratory workup to ensure a comprehensive clinical picture. Such approaches can aid in early intervention and quicker improvement in patient symptoms and well-being.