A 39-year-old woman, who is a sanitation worker, unmarried and nulliparous, was admitted to our hospital because of linear-erythema with accompanying pruritus and formication in her left upper arm for 1 month. The lesion appeared after she had cleared the grass in the highway greening zone. The linear erythema was misdiagnosed as eczema in her local hospitals. She also received a topical therapy with mometasone furoate cream to alleviate pruritus. One week before the admission, the skin lesion gradually spread to the proximal part of the upper limbs, and the intense pruritus severely affected her sleep, work, and quality of life. Hence, she came to our hospital. She denied hepatitis, tuberculosis, or other infectious diseases, and had no history of smoking, drinking, allergies, or surgery. On admission, dark red, linear, spiral patches were seen on the lateral side of the upper arm. The lesion was well-circumscribed with a slightly raised border, and no ulcerations or erosions (Figure 1A and B).
Laboratory testing showed completely normal humoral and cellular immune function. A blood test revealed a white blood cell count of 7.10 x 109/L (reference range: 4.0-10.0 x 109/L), eosinophil count of 1.3 x 109/L (reference range: 0.02-0.35 x 109/L), and eosinophil percentage of 18.5% (reference range: 0.005-0.050%). Her routine urine test was normal. At the same time, we performed a dermoscopy examination of the patient's lesion, and found that linear, light-yellow, and dark red block area of unequal width was a tunnel burrow, formed in the stratum corneum by larva migration (Figure 2A). We also saw translucent round structures from the apex of the linear lesion, which had several high refractive dots internally, which might be the larval body or paws (Figure 2B).
The lesion was assessed by RCM which showed edema in the epidermis and superficial dermis, and a well-circumscribed, oval-shaped tunnel in the stratum corneum or granular layer, which could extend to the superficial dermis (Figure 3A). At one end of the tunnel, there was a well-delineated ovoid larval body and claw-like structures (Figure 3B).
Based on clinical presentation, dermoscopy, and RCM, the patient was finally diagnosed with CLM. The patient was treated with cryotherapy. Attention should be paid to the scope, time, depth, and frequency of cryotherapy, to avoid obvious scars, which could be formed by excessive treatment. Liquid nitrogen was applied to the patient's both ends of the skin rash several times using a cotton swab. After 3 days, the linear rash continued to migrate, requiring extending cryotherapy to all lesions. Seven days later, the rash still spread to the proximal part of the left upper arm and left shoulder (Figure 4A and B). Thus, dermatoscopy and RCM were performed to accurately locate the position of the larvae in the skin lesions, which were then frozen. After 14 days, the patient's pruritus significantly reduced, and the rash did not spread. Three weeks later, the lesion was completely cured, and the skin rash was completely resolved. At this time, a routine blood test showed, a white blood cell count of 8.18 x 109/L (reference range: 4.0-10.0 x 109/L), eosinophil count of 0.3 x 109/L (reference range: 0.02-0.35 x 109/L), and eosinophil percentage of 3.7% (reference range: 0.5-5.0%), and routine urine test was normal. No recurrence was noted after 2 months (Figure 5A and B).