Squamous Cell Carcinoma Arising From an Epidermal Cyst of the Buttock

A Case Report

Michika Fukui, MD; Natsuko Kakudo, MD, PhD; Naoki Morimoto, MD, PhD; Masakatsu Hihara, MD; Hiromu Masuoka, MD; Kenji Kusumoto, MD, PhD

Disclosures

ePlasty. 2019;19(ic18) 

In This Article

Case Description

A 70-year-old man presented with a mass on his right buttock, which measured 7 × 7 cm in diameter (Figure 1), and a swelled right inguinal lymph node. He noticed the mass 20 years ago. It was infected and discharged pus, and recently it has been growing rapidly. Antibiotics were ineffective. Magnetic resonance imaging showed that it had invaded the subcutaneous region (Figures 2a-2d). We excised it with a 3-cm surgical margin and the muscle fascia, as well as the swelled lymph node (Figures 3a and 3b). Histopathologically, this case was diagnosed as a squamous cell carcinoma arising from an epidermal cyst and right inguinal lymph node metastasis, because the epithelium of the squamous cell carcinoma was contiguous with the epithelium of the epidermal cyst (Figures 4a and 4b). A skin graft and lymph node dissection were performed (Figure 4c). There was no recurrence of the tumor (Figure 4d).

Figure 1.

Preoperative findings. A 70-year-old man with a tumor (7×7 cm) on his buttock.

Figure 2.

(a) Axial T1-weighted MRI scan of the tumor. (b) Axial T2-weighted MRI scan of the tumor. (c) Sagittal T1-weighted MRI scan of the tumor. (d) Sagittal T2-weighted MRI scan of the tumor.

Figure 3.

(a) Design of the operation. (b) Image obtained after the tumor was resected.

Figure 4.

(a) Epithelial findings. The epithelium of the squamous cell carcinoma is contiguous with the epithelium of the epidermal cyst (hematoxylin and eosin staining, bar: 5 mm). (b) Cellular findings. Numerous keratinized atypical cells are seen. The atypical cells have formed nests and cancer pearls (hematoxylin and eosin staining, bar: 1 mm). (c) Postoperative findings obtained after the skin grafting. (d) Postoperative 6-month findings.

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