Race for the Case answers

Answers to Fall 2020 Race for the Case by Angelia Stepien, DO, and Preetha Kamath, MD

A 74-year-old Caucasian male with a history of squamous cell carcinoma, hypertension, and hyperlipidemia presented with a solitary lesion over the left lateral lower leg. On physical exam, a single erythematous infiltrative plaque with an anesthetic center was noted. Decreased sensation to touch was present on the plantar surface of the left foot. He denied pain, itching, fever, cough, or chills. The patient reported Florida residence of over 20 years. He denied recent trauma, international travel, or animal exposure. Well-formed granulomas throughout the dermis and perineurally were noted on histopathology. Fite and AFB were negative for organisms. The specimen was sent for PCR and slit-skin smear microscopic evaluation.

1. What is the diagnosis and causative agent?
   Answer: Leprosy, also known as Hansen’s disease. Mycobacterium leprae (M. leprae) is the causative agent in a majority of cases

2. What is the name of the classification system which polarizes the five subtypes of this disease based on a patient’s cell-mediated immunity? Which would this patient be classified as?
   Answer: Ridley-Jopling spectrum: tuberculoid (TT), borderline tuberculoid (BT), midborderline (BB), borderline lepromatous (BL), and lepromatous (LL). This patient demonstrated TT type

3. What is the organism’s ideal temperature for growth?
   Answer: 35°C

4. What is the mode of transmission?
   Answer: Nasal or oral droplets and much less often eroded skin. Zoonosis in southeastern U.S. — nine-banded armadillos (others include red squirrels in British Isles and mice)

5. What HLA subtypes are associated with this condition?
   Answer: HLA-DQ1 (lepromatous), HLA-DR2, and HLA-DR3 (tuberculoid)

6. Which antibody is associated with reactions and impaired nerve function
   Answer: Anti-PGL-1 IgM

7. For how many years after treatment completion should patients be screened?
   Answer: After completion of multidrug therapy, the National Hansen’s Disease Program advises paucibacillary patients to be screened annually for 5 years and multibacillary patients for 8 years.

List of abbreviations:

AFB: acid-fast bacilli
PCR: polymerase chain reaction
HLA: human leukocyte antigen
PGL-1: phenolic glycolipid-1
IgM: immunoglobulin M

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