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A 54-year-old woman presented with a 7-year history of a painful subungual mass of the right thumb. The lesion was initially believed to be an infection; however, results of both mycological and bacteriologic examinations were unremarkable. The patient had no notable medical history, including dyskeratosis congenita, trauma, sun exposure, radiation exposure, chemical exposure to tar or arsenic or exposure to minerals, chronic immunosuppression, or chronic infection. Physical examination revealed a subungual nodule with some exudation and crusts. The distal nail plate had been destroyed and showed onycholysis with obvious separation from the nail bed (Figure, A). Pertinent laboratory results (complete blood cell count, liver panel, kidney panel) were within normal limits. Lesional biopsy was also performed (Figure, B and C).
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B. Subungual squamous cell carcinoma
Malignant subungual tumors are rare and are associated with subungual squamous cell carcinoma (SCC), Bowen disease, melanoma, basal cell carcinoma, and subungual keratoacanthoma among others. Of these malignant neoplasms, subungual SCC is the most frequent.1- 4 Subungual SCC has been considered a low-grade malignant neoplasm with a good prognosis compared with SCC arising elsewhere.2- 4 About 20% of patients with subungual SCC have bony invasion, and metastasis and lymph node involvement is uncommon.1- 4 Usually, the patients tend to be men aged 50 to 79 years, and typically, a single digit, especially the thumb or hallux, is likely to be involved.1- 3
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Corresponding Author: Jun Li, MD, Department of Dermatology, Peking Union Medical College Hospital, No. 1 Shuaifuyuan Wangfujing, Dongcheng District, Beijing 100730, China (firstname.lastname@example.org).
Published Online: October 31, 2019. doi:10.1001/jamaoncol.2019.4500
Conflict of Interest Disclosures: Drs Gong and Li reported support by the National Key Research and Development Program of China (No. 2016YFC0901500).
Additional Contributions: We thank the patient for granting permission to publish this information.
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