Guiyun Zhang,1 Yufeng Lu,2 Lin Qi,1 Chunli Yao1 

1Department of Dermatology, The Second Hospital of Jilin University, Changchun, 130041, People’s Republic of China; 2Department of Thoracic Surgery, Sino-Japanese Friendship Hospital of Jilin University, Changchun, 130012, People’s Republic of China

Correspondence: Chunli Yao, Department of Dermatology, The Second Hospital of Jilin University, Changchun, 130041, People’s Republic of China, Tel +86-431-81136244, Email ycl@jlu.edu.cn

Introduction: Rare studies have reported pilomatricoma in twins, and extremely rare cases showed lesions in the same part of the body position. We reported a case of monozygotic twins with pilomatricoma in the same location on the skin of the right upper extremity.
Case Presentation: Seven-year-old monozygotic twins presented to our department with a palpable, painless, and solid mass in the subcutaneous tissue of the right upper limb. A 1.5-cm diameter nodule was seen on the anterolateral aspect of the right upper extremity of the twins. The node was irregular in shape, and upon palpation, the patients reported no noticeable tenderness. Following the administration of local anesthesia, the twins underwent surgical procedure to excise the solid mass. Finally, they were diagnosed with pilomatricoma based on the clinical and histopathological features. Complete surgical resection followed by primary closure was performed. During a follow-up period of three years, there has been no recurrence observed in the twins.
Conclusion: We reported a case of monozygotic twins with pilomatricoma in the same location on the skin of the right upper arm. Our findings underscore the requirement of considering genetic factors in the diagnosis and treatment of the rare conditions.

Keywords: pilomatricoma, pilomatrixoma, calcifying epithelioma of malherbe, case report