Department of Dermatology, Juntendo University Urayasu Hospital.
Ochanomizu Institute for Medical Mycology and Allergology.
Med Mycol J. 2024;65(4):103-106. doi: 10.3314/mmj.24-00010.
A man in his thirties patient visited his previous physician with the chief complaint of a pigmented macule on the sole of his left foot that had steadily grown over the past two years. A dermoscopic examination of the lesion showed a parallel ridge pattern (PRP); therefore, acral-lentiginous melanoma (ALM) was suspected, and the patient was referred to our hospital for a more detailed examination. On closer inspection, PRP had a well-defined and irregular border with no variation in color, which is atypical for ALM which is characterized by asymmetrical structure and variation in colors. Therefore, a skin biopsy was performed for a definite diagnosis, and the histopathological findings showed mycelia in the horny layers. Fungal culture revealed Hortaea werneckii, and the patient was diagnosed with tinea nigra (TN). Although TN is a rare fungal infection in Japan, we emphasize that this fungal infection should be noted as a mimic of ALM and should be considered when PRP is detected on the palms and soles by dermoscopic examination.
一位 30 多岁的男性患者因左足底的色素斑在过去两年中逐渐增大而就诊于他之前的医生。病变的皮肤镜检查显示平行脊状模式（PRP）；因此，怀疑肢端雀斑样黑素瘤（ALM），并将患者转至我院进行更详细的检查。仔细观察，PRP 边界清晰且不规则，颜色无变化，这与 ALM 不同，后者的特征是结构不对称和颜色变化。因此，进行了皮肤活检以明确诊断，组织病理学检查显示角质层中有菌丝。真菌培养显示 Werneckii 小孢子菌，患者被诊断为黑癣（TN）。尽管 TN 在日本是一种罕见的真菌感染，但我们强调，这种真菌感染应该被认为是 ALM 的模拟，并且当通过皮肤镜检查在手掌和足底检测到 PRP 时应该考虑到。
