Pleomorphic Rhabdomyosarcoma of the Uterine Corpus: A Clinicopathologic Study of 4 Cases and a Review of the Literature

We report the clinicopathologic features of 4 cases of pure pleomorphic rhabdomyosarcoma of the uterine corpus with an emphasis on their frequent expression of CD10 and CD56, review the relevant literature, and discuss differential diagnostic considerations. The patients ranged from 51 to 79 years (mean 68 y). All were FIGO stage IIIC to IV at initial surgical staging, and 3 were dead from the disease at an average of 8.6 months follow-up. In addition to the expected findings, other notable morphologic features included tumor giant cells (4/4), osteoclast-like giant cells (1/4), patchy myxoid stroma (4/4), and only infrequent cytoplasmic cross striations (1/4). The tumors in all 4 cases were positive for myogenin, myo-D1, smooth muscle actin, desmin, muscle-specific actin (HHF-35), and CD10; 3 (75%) of 4 cases were positive for calponin and CD56; all cases were negative for cytokeratin 7, synaptophysin, epithelial membrane antigen, placental-like alkaline phosphatase, chromogranin, and a pan-keratin. Twenty-three cases have been reported earlier in the English-language literature between 1969 and 2009. In combination with the current 4, the 27 patients had an age range of 35 to 87 years (mean 66.33 y). Only 1 patient was deemed inoperable; most had staging operations. Following their initial evaluations, 16 (59%) were found to have extrauterine extension of disease. At follow-up, 73% (19/27) were dead from the disease and 19.2% had no evidence of recurrence. Ten (53%) of the 19 deaths occurred within 6.5 months of initial evaluation. Stage at presentation did not have any significant impact on outcome: 73% of the 11 patients with uterus-confined disease at presentation were dead from the disease at follow-up, a rate of disease-associated death that was nearly identical to the 75% in the 16 patients with extrauterine disease at presentation. A wide variety of neoadjuvant and adjuvant therapies were administered, which did not appear to significantly impact outcomes. These data indicate that pleomorphic rhabdomyosarcoma of the uterine corpus is a highly aggressive, rapidly progressive tumor with a high case-fatality rate.