Dermal Cystine Crystals: An Incidental Finding During Mohs Surgery

Area of Science:

• Dermatology and Pathology
• Genetics and Metabolic Disorders

Background:

• Cystinosis is an autosomal recessive lysosomal storage disorder due to CTNS gene mutations, leading to intracellular cystine accumulation.
• Patients with cystinosis may have an increased risk of developing carcinomas, particularly after renal transplantation.

Observation:

• A 48-year-old woman with a history of cystinosis and squamous cell carcinoma underwent Mohs micrographic surgery.
• Frozen sections of Mohs surgical layers revealed widespread deposition of intracellular cystine crystals in dermal fibroblasts and macrophages.
• These crystals exhibited characteristic rectangular to polygonal shapes and were highlighted by polarized light microscopy.

Findings:

• Frozen section processing is an effective method for visualizing intracellular cystine crystals in the context of Mohs surgery.
• The presence of cystine crystals can be an unusual finding during the evaluation of skin cancer slides in patients with cystinosis.

Implications:

• Mohs surgeons should be aware of the potential for cystine crystal deposition when examining slides from patients with cystinosis.
• Recognition of this phenomenon is crucial for accurate diagnosis and appropriate patient management, especially in post-transplant scenarios.