PMC6280225_01
(a) Appearance of the mass at initial presentation. (b) Ultrasound revealed a hyperechoic, well-circumscribed mass.
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fig1
His primary care physician referred him for ultrasound fine needle aspiration of the abscess, which yielded 15 cc of purulent material (Figure 1).
(a, b) Mass measured at 4 cm; the medial margin borders of the gluteal cleft. (c, d) The defect is undermined and closed primarily.
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fig2
It was decided to excise the mass completely and close the defect primarily (Figure 2).
(a) A nodular, well-circumscribed basophilic tumor involved the dermis and displayed areas of cystic architecture (arrows). (b) The tumor cells were basaloid, small, hyperchromatic, and mostly uniform. Nodules exhibited peripheral palisading cells and retraction artifact (arrows). (c) Islands of mucin (arrows) were present within the tumor. (d) Some tumor nodules exhibited dark-brown pigment centrally. (e) The pigment was coarse and acellular. (f) Desmoplastic stroma harboring cholesterol clefts (arrows) and clumps of pigment was seen in nodule centers. (a-f) Hematoxylin and eosin: (a) 20x, (b) 40x, (c) 100x, (d) 40x, (e) 200x, and (f) 100x.
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Microscopically, a nodular well-circumscribed tumor was present in the dermis (Figure 3(a)) and displayed peripheral palisading cells, desmoplastic changes, and retraction artifact. Tumor cells were small, mostly uniform in shape, and hyperchromatic (Figure 3(b)). The tumor produced mucin which was seen as aggregates within the nodules (Figure 3(c)). Foci of dark-brown acellular pigment consisting of coarse clumped granules were found in the lesion (Figures 3(d) and 3(e)), and some tumor nodules displayed a dense fibrous stroma containing pigment clumps and cholesterol clefts.
Healed incision site at 10 months postoperatively.
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At two-year follow-up evaluation, there had been no recurrence or complications (Figure 4).