PMC7178868_01
Clinical findings and MRI images. (A) A reddish mass of 4-mm diameter is seen under the nail plate (area surrounded by the triangle mark). Distal nail splitting is observed in the left thumb. (B) T1-weighed magnetic resonance image shows tumor with normal intensity. (C) T2-weighed magnetic resonance image shows high-intensity lesion. Flow void is indicated by an arrow. MRI: magnetic resonance imaging.
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The tumor was 4 mm in diameter and the nail bed proximal to the tumor was slightly elevated (Figure 1(A)). The tumor presented with normal intensity on T1-weighed image (Figure 1(B)) and was hyperintense on T2-weighed image (Figure 1(C)).
Surgical findings. (A) A reddish mass is seen under the nail plate. The excision line after the nail claw is indicated in blue. (B) After excision, skin grafting was performed from the thenar eminence.
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The tumor could be resected completely (Figure 2(A)). The defective nail matrix was reconstructed with a glabrous dermal graft (Figure 2(B)) taken from the thenar of the right thumb.
Histopathological findings. (A) A loupe image. An incompletely encapsulated tumor. (B) A middle-power view. The tumor is composed of fine collagen fibers pointed in every direction. (C) A high-power view. Nuclei of the proliferating cells are spindle- or comma-shaped. Among the tumor cells, capillaries and a small number of mast cells are dispersed (indicated by arrows). (D) Appearance of new thumb nail six months postoperatively. This observation is natural.
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Histological examination of the excised specimen showed an incompletely encapsulated eosinophilic fibrous tumor (Figure 3(A)). The tumor was composed of fine collagen fibers with numerous scattered cells with spindle- and comma-shaped nuclei (Figure 3(B,C). A small number of the mast cells were observed within the tumor (Figure 3(C)). Postoperatively, the nail re-grew with a good cosmetic result (Figure 3(D)).