The American Society of Dermatopathology

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Interactive Case Study - June 2013

Solitary mass on the right thigh of an adolescent

Steven A. Nelson; Tammie Ferringer, MD; George Lin, MD, PhD

Question 1:

A previously healthy 12-year-old female presented with an enlarging mass on the right posterior thigh. A 4 x 5 cm tumor was palpable superior to the popliteal fossa of the right leg with no overlying skin changes. The tumor cells demonstrate nuclear labeling with TLE1 immunohistochemical studies. The histology is shown in Figures 1-4.

Figure 1. H&E 40x

Figure 2. H&E 100x

Figure 3. H&E 200x

Figure 4 H&E 400x

Which of the following is the best diagnosis?