Scrub Typhus Presenting with Leukocytoclastic Vasculitis and a Palmoplantar Rash: An Atypical Presentation

1. Introduction

Scrub typhus is an acute febrile zoonosis caused by the obligate intracellular bacterium Orientia tsutsugamushi, transmitted to humans through the bite of larval-stage trombiculid mites (chiggers). It is endemic across the “tsutsugamushi triangle” of tropical and subtropical Asia, including large parts of rural India, and remains an important yet frequently under-diagnosed cause of acute undifferentiated febrile illness.[1,4,11,12]

The clinical spectrum ranges from a self-limiting febrile illness to severe multiorgan dysfunction. Classic teaching emphasises fever, headache, myalgia, an inoculation eschar at the mite-bite site, and a truncal maculopapular rash; however, clinical reviews and contemporary epidemiological data show that these cutaneous findings are variable and not universal, which can lead to diagnostic delay.[1,13,16] The underlying pathophysiology is a focal or disseminated vasculitis and perivasculitis driven by direct invasion of vascular endothelial cells and macrophages, with organ tropism for the lungs, heart, liver, spleen, kidneys, and central nervous system; this systemic vascular involvement underlies the broad clinical spectrum and severe multiorgan disease.[8,9,13]

Cutaneous leukocytoclastic vasculitis (LCV) as the presenting or dominant skin finding in scrub typhus is rarely reported and can be mistaken for other causes of small-vessel vasculitis, delaying appropriate antirickettsial therapy. We describe a case of scrub typhus in which the patient initially had neither eschar nor rash, and subsequently developed a biopsy-confirmed leukocytoclastic vasculitis with a distinctive palmoplantar distribution — a presentation that broadens the recognised cutaneous phenotype of this disease.

2. Case Presentation

2.1 History

A 55-year-old female daily-wage labourer presented with a two-week history of non-radiating neck pain of insidious onset, progressive and aggravated by exertion, associated with giddiness. There was no weakness of the limbs, speech disturbance, tinnitus, blurring of vision, or diplopia. Seven days prior to presentation she had experienced fever with chills, headache, and generalised myalgia, which was partially treated at a local clinic with intravenous fluids and a short course of chloramphenicol. There was no history of altered sensorium, nausea, vomiting, ear/nose/throat symptoms, respiratory or cardiac symptoms, or urinary or gastrointestinal complaints.

Her past history was notable for cervical spondylosis on treatment; she was not a known diabetic, hypertensive, or diagnosed with tuberculosis, bronchial asthma, epilepsy, or ischaemic heart disease. Personal history included a mixed diet, regular bowel and bladder habits, and 37 years of areca (betel) nut chewing. Menstrual history was unremarkable, with menopause at age 47.

2.2 Examination at admission

The patient was conscious, oriented, and moderately built and nourished (height 155 cm, weight 51 kg, BMI 21.2 kg/m²). Pallor was present; there was no icterus, cyanosis, clubbing, pedal oedema, or lymphadenopathy. Vital signs were stable: pulse 80/min regular, blood pressure 110/70 mmHg (right arm) and 100/70 mmHg (left arm), respiratory rate 14/min, temperature 98.4°F, and oxygen saturation 98% on room air, with a normal jugular venous pressure. Systemic examination (cardiovascular, respiratory, abdominal, and neurological) was unremarkable, with no focal neurological deficit or meningeal signs. Local examination of the head, face, oral cavity, eyes, ears, nose, trunk, extremities, and joints was normal, with no eschar or rash noted at this stage.

2.3 Initial investigations

Mild transaminitis and a markedly elevated erythrocyte sedimentation rate (ESR) were the only notable abnormalities; the leukocyte and platelet counts, renal function, and urinalysis were normal.

2.4 Clinical evolution

On the second day of admission the patient developed high-grade continuous fever (up to 102°F) with chills and rigors, accompanied by bilateral conjunctival redness (Figure 1). This was shortly followed by an itchy maculopapular rash with a red base, both discrete and confluent, distributed over both extremities with striking concentration on the palms and soles; there was no mucosal involvement (Figure 2).

2.5 Differential diagnosis

Given the constellation of fever with a peripheral maculopapular rash and transaminitis, a broad infectious differential was considered, including dengue fever, rickettsial disease, leptospirosis, meningococcal disease, secondary syphilis, and infective endocarditis. Given the recent short course of chloramphenicol, drug-induced vasculitis was also considered. Empirical antibiotics and supportive management were started while further investigations were pending.

2.6 Further work-up

Dermatology and ophthalmology opinions were sought; a skin punch biopsy was performed, and blood investigations were repeated alongside serological testing for HIV, hepatitis B surface antigen (HBsAg), anti-hepatitis C virus (anti-HCV) antibodies, dengue, leptospirosis, and scrub typhus, together with abdominal ultrasonography.

Serology confirmed scrub typhus, while dengue, leptospirosis, HIV, HBsAg, and anti-HCV were negative/non-reactive, blood cultures were sterile, and imaging (abdominal ultrasound, chest radiograph, and ECG) was normal.

2.7 Histopathology

Skin punch biopsy from a representative lesion demonstrated perivascular neutrophilic infiltration, endothelial cell swelling, and nuclear dust with fibrinoid necrosis of the vessel wall (Figure 3 and 4) — findings diagnostic of leukocytoclastic vasculitis.

2.8 Treatment and outcome

With the diagnosis of scrub typhus established, the patient was treated with oral doxycycline 100 mg twice daily, along with desloratadine for pruritus, paracetamol for fever, and topical/ophthalmic moxifloxacin and lubricant eye drops on ophthalmology advice. Fever settled after five days of antibiotic therapy, the rash began to resolve, and the patient improved symptomatically. She was discharged in a clinically stable condition with advice for outpatient follow-up; however, documented long-term follow-up was not available.

3. Discussion

Although eschar and truncal rash are considered classic cutaneous markers of scrub typhus, large endemic-area series show that neither finding is universal: pooled estimates report eschar in roughly one-fifth and rash in only about 5% of confirmed cases, with wide variation between cohorts.[1] Our patient initially had neither finding, and her presenting complaints — neck pain and giddiness following a partially treated febrile illness — were nonspecific, illustrating how atypical presentations can obscure the diagnosis until more classic features emerge later in the illness course.

The pathogenetic hallmark of scrub typhus is focal or disseminated vasculitis and perivasculitis, resulting from direct invasion of endothelial cells and macrophages by O. tsutsugamushi and the accompanying host immune response, with organisms disseminating haematogenously and via lymphatics to the liver, spleen, lungs, kidneys, heart, and brain.[8,9] This vasculitic process underlies both the classic cutaneous findings (eschar and rash) and the severe systemic complications reported in the literature, including acute kidney injury, myocarditis, hepatic dysfunction, meningoencephalitis, splenic infarction, and, in extreme cases, digital gangrene from disseminated small-vessel occlusion.[7,9,10] Renal involvement has similarly been attributed to multiorgan small-vessel vasculitis, disseminated intravascular coagulation, or prerenal hypoperfusion from capillary leak.[9]

Leukocytoclastic vasculitis is a histopathological pattern of small-vessel injury characterised by neutrophilic transmural inflammation of post-capillary venules, karyorrhexis of neutrophil nuclei producing “nuclear dust,” extravasation of red blood cells, and fibrinoid necrosis of the vessel wall; if biopsy is delayed beyond 48–72 hours, the infiltrate may shift to a predominantly mononuclear pattern. LCV has a broad differential that includes IgA vasculitis (Henoch-Schönlein purpura), urticarial vasculitis, cryoglobulinaemic vasculitis, ANCA-associated vasculitides, connective tissue disease, drug reactions, neoplasia, and infection. In this patient, the clinical context, microbiological evaluation, positive scrub typhus serology, and response to doxycycline supported an infectious trigger; however, a complete autoimmune vasculitis work-up was not performed and a primary autoimmune etiology cannot be completely excluded.[2,3]

A small number of prior case reports have similarly described scrub typhus presenting with cutaneous leukocytoclastic vasculitis, at times accompanied by polyarthralgia, reinforcing that this is a genuine although uncommon disease phenotype rather than an isolated curiosity.[5,6,7,16] The palmoplantar predominance of the rash in our patient is a further point of interest, as this distribution is not typically emphasised in descriptions of the classic scrub typhus exanthem and may reflect the acral vascular bed's particular vulnerability to the underlying vasculitic process.

From a practical standpoint, this case underscores two teaching points. First, in patients from endemic regions presenting with unexplained fever, elevated inflammatory markers, and a vasculitic-appearing rash — even without an eschar — scrub typhus should remain an important differential diagnosis, given the substantial burden of disease in India and the variability of its cutaneous manifestations.[12,17] Second, the rapid defervescence and clinical improvement following doxycycline, together with a positive ELISA, supported scrub typhus as the most likely infectious trigger in the absence of confirmatory indirect immunofluorescence or PCR, which constitutes a limitation of this report. Drug-induced vasculitis was also considered because of the recent short course of chloramphenicol; however, the preceding febrile illness, subsequent fever with conjunctival injection and vasculitic rash, positive scrub typhus IgM, and response to doxycycline favoured an infectious trigger. Nevertheless, drug-induced vasculitis cannot be completely excluded in the absence of specific testing or rechallenge. Contemporary diagnostic studies support IgM ELISA as a useful clinical test while highlighting the value of molecular confirmation, particularly early in illness.[14,15]

CRP was not measured during the admission, representing a limitation in the assessment of the inflammatory response and its temporal change following treatment. In addition, the absence of documented long-term follow-up and a comprehensive autoimmune vasculitis work-up limits definitive exclusion of an underlying primary vasculitic disorder.

4. Conclusion

Scrub typhus should be considered in the differential diagnosis of acute febrile illness with a vasculitic or atypical cutaneous eruption, even in the absence of a characteristic eschar. This case highlights leukocytoclastic vasculitis with a prominent palmoplantar rash as an uncommon cutaneous manifestation of scrub typhus and demonstrates the value of skin biopsy when the clinical presentation is atypical. In endemic settings, maintaining a high index of suspicion and initiating appropriate antirickettsial therapy promptly may facilitate early diagnosis and prevent progression to potentially severe systemic disease.

Declarations

Ethics statement

Ethical approval was not required for this single-patient case report in accordance with institutional policies.

Consent for publication

Written informed consent was obtained from the patient for publication of this case report and accompanying clinical images. Identifying features have been cropped from the photographs to protect patient anonymity.

Author Contributions

MN and KM: conceptualization, clinical evaluation, data collection, literature review, and manuscript drafting. PM, MY, and GK: clinical evaluation, supervision, and critical revision of the manuscript. All authors reviewed and approved the final version of the manuscript and agree to be accountable for all aspects of the work.

Conflict of interest

The authors declare no conflict of interest.

Funding

Publisher’s Note

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