Endgames Picture Quiz

A 45 year old man with an ulcerated nodule on his right leg

BMJ 2014; 349 doi: https://doi.org/10.1136/bmj.g5296 (Published 08 September 2014) Cite this as: BMJ 2014;349:g5296
  1. Pablo Fernández-Crehuet, dermatologist1,
  2. Ricardo Ruiz-Villaverde, dermatologist2
  1. 1Dermatology Department, Alto Guadalquivir Hospital, Andújar, Jaén, 23740, Spain
  2. 2Dermatology Department, Complejo Hospitalario de Jaén, Jaen, Spain
  1. Correspondence to: P Fernández-Crehuet pablocrehuet{at}hotmail.com

A 48 year old man presented to our dermatology clinic because of an asymptomatic skin nodule on his right leg that had appeared several weeks earlier. He had no medical history of note. On further questioning, he mentioned that he had received an arthropod bite at that site during the previous summer. He was initially treated with a three week course of doxycycline 200 mg per day and topical mupirocin 2% as empirical treatment for Mediterranean spotted fever, which is endemic in our geographical area, pending the results of blood cell count, general biochemistry, and Borrelia burgdorferi serology. However, the main clinical symptoms of Mediterranean spotted fever—fever, weight loss, musculoskeletal pains, and neurological symptoms—were absent. On examination, chest, abdomen, and eye examinations were normal. The nodule on his anterior right leg was 4 cm in size, ulcerated, and indurated, with a raised border and central serous crust (fig 1). Polarised non-contact dermoscopy of the nodule showed basal erythema, central ulceration, and hyperkeratosis with peripheral arborising telangiectasias, and peripheral “yellow tears” (fig 2).

Fig 1 Erythematous plaque with serous central crust on the right leg

Fig 2 Polarised light dermoscopy showing erythema, central ulceration, and hyperkeratosis with peripheral arborising telangiectasias and peripheral “yellow tears”

Questions

  • 1. What is the cause of the skin condition and what are the main differential diagnoses?

  • 2. What investigations would you do to confirm the underlying diagnosis?

  • 3. How would you treat this condition?

Answers

1. What is the cause of the skin condition and what are the main differential diagnoses?

Short answer

The skin condition is caused by old world cutaneous leishmaniasis. The differential diagnoses include other dermatoses transmitted by arthropod bites, such as Lyme disease and Mediterranean spotted fever.

Long answer

Leishmaniasis is a protozoan parasitic disease transmitted by the bite of certain species of the infected female sand fly (subfamily Phlebotominae). The most common vectors are mosquitoes of the genuses phlebotomus and …

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