Case Study: Differentiating Arthropod Bites from Scabies in a Young Adult

Case at a Glance

A 27-year-old female presented with an acute onset of skin bumps following a hotel stay. Despite her concern for scabies, the clinical picture, including a lack of new lesions and minimal pruritus, along with a negative skin scraping, pointed towards a diagnosis of arthropod bites.

Patient's Story

The patient, a 27-year-old female with no significant past medical history, presented for evaluation of several bumps that appeared suddenly. She reported a recent stay in a hotel and was concerned about a possible scabies infestation. However, she noted that the bumps had not spread and no new lesions had appeared in the week since their initial discovery. The pruritus was described as mild and only occurred upon direct palpation of the lesions, which is atypical for the intense, often nocturnal, itching associated with scabies.

Initial Assessment

Upon presentation to a dermatology clinic, the primary differential diagnosis was arthropod bites, likely from bed bugs, given the patient's recent travel history. The clinical presentation of discrete papules without evidence of burrows, combined with the patient's report of minimal itching and no new lesions, made scabies less likely. A peer opinion also suggested that the lack of intense itching and burrows was inconsistent with a typical scabies presentation.

The Diagnostic Journey

To address the patient's concerns and formally investigate the possibility of scabies, a skin scraping was performed on one of the lesions. The sample was examined microscopically for mites, eggs, or scybala. The result of the skin scraping was negative. The dermatologist informed the patient that while a negative scraping does not entirely rule out scabies due to its relatively low sensitivity, the test result, in conjunction with the atypical clinical course (non-progressive rash, mild contact-based itch), strongly supported the initial diagnosis of arthropod bites.

Final Diagnosis

Probable Arthropod Bites (Cimicosis), with scabies considered highly unlikely.

Treatment Plan

No specific anti-scabietic treatment was initiated. The patient was advised on symptomatic relief for the existing bites, such as using an over-the-counter hydrocortisone cream if the itching increased. She was also counseled to monitor her skin for any new lesions, which would warrant a re-evaluation. No further investigation or treatment was deemed necessary at the time.

Outcome and Follow-up

The patient was instructed to follow up only if new symptoms developed or if the existing lesions worsened. Given that the rash had been stable for a week, a spontaneous resolution was expected. The clinical course confirmed the diagnosis, as no new bumps appeared and the initial lesions likely faded without intervention, consistent with a self-limited reaction to bites rather than an active, ongoing infestation.