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.