Leiomyoma With Bizarre Nuclei: Clinical and Pathologic Features of 30 Patients.

Leiomyoma with bizarre nuclei (LBN) have significant cytologic atypia, but high mitotic rate and tumor cell necrosis are absent. Although it is a benign leiomyoma variant, recurrent cases have been described. In this study, we investigated the clinical and pathologic features of LBN and compared them with related studies. A total of 30 patients diagnosed with LBN in our department were included in this study. In all cases, clinical data (age, complaint, surgery type), macroscopic features (size, location, number of leiomyomas, necrosis, and hemorrhage), microscopic features (bizarre cell distribution, bizarre cell density, cellularity, mitotic rate, tumor margin, necrosis, nuclear pseudoinclusions, karyorrhectic nuclei, prominent eosinophilic nucleoli with perinucleolar clearing, cytoplasmic eosinophilic inclusions, staghorn vessels, and alveolar-type edema), and follow-up data (recurrence and survival period) were evaluated. The mean age of the patients was 49.76 yr (range: 38-89 yr). Twenty-two patients (73%) had undergone hysterectomy and 8 patients (27%) had undergone myomectomy. The mean tumor diameter was 6.12 cm (range: 0.5-25 cm). The tumor was intramural in 11 patients (37%), subserosal in 7 patients (23%), and submucosal in 4 patients (13%). Microscopically, the bizarre cell distribution was focal in 8 patients (27%), multifocal in 12 patients (40%), and diffuse in 10 patients (33%). Bizarre cell density was low in 15 patients (50%), intermediate in 8 patients (27%), and high in 7 patients (23%). The mean mitotic count was 1.4 (0-4) in 10 high-power fields, and the tumor margin was regular in all cases. We observed pseudoinclusions in 24 of 30 (80%) tumors, karyorrhectic nuclei in 21 of 30 tumors (70%), prominent eosinophilic nucleoli with perinucleolar clearing in 12 tumors (40%), cytoplasmic eosinophilic inclusions in 11 tumors (37%), staghorn vessels in 9 tumors (30%), and alveolar-type edema in 9 tumors (30%). In addition, we examined the follow-up records of 26 patients (average duration: 58.1 mo). One patient had a smooth muscle tumor in the L3-L4 paravertebral region at 67 mo after hysterectomy. This tumor did not share similar microscopic and immunohistochemical findings to the patient's earlier uterine tumor. The definitive diagnosis of uterine smooth muscle tumors is important for the determination of the prognosis of the patient and the most appropriate therapeutic approach. As in several recent studies, our series has shown that LBN has a benign clinical course. However, other malignant morphologic criteria such as high mitotic rate and tumor cell necrosis should be excluded in the diagnosis of LBN.