Benign Metastasizing Leiomyomatosis

Abstract

The authors report an interesting case of a minimally symptomatic 23-year-old African American woman who was found to have extensive diffuse reticulonodular opacities of the lungs on a routine chest radiograph. She had a hysterectomy 5 years previously for multiple leiomyomas of the uterus. She had no history of any prior exposure to dusts or toxins. Collagen vasculitides and bacterial, mycobacterial, and fungal infectious causes were excluded through standard testing, and a bronchoscopic lung biopsy was nonspecific. An open lung biopsy revealed multiple nodules of proliferating smooth muscle cells intermixed with irregular areas of epithelial-lined spaces. Histologically, the muscle cells appear benign with a very low mitotic rate, and the pathologic findings were consistent with benign metastasizing leiomyomatosis (BML). Staining for estrogen and progesterone receptors, actin, and c-kit were performed. This case and the review of the medical literature support the concept that BML originates from an antecedent leiomyoma of the uterus in virtually all cases with rare exceptions. It appears that tumor metastasizes to lungs or other extrauterine tissues via hematogenous spread. However, the origin of the tumor remains controversial. BML is a rare entity, with only a handful of reports in the medical literature. The authors report an interesting case of BML in a 23-year-old patient who, to their knowledge, is the youngest such patient described and who, at 13 years, has the longest period of clinical follow-up. In this article, the authors review the pathogenesis, cytogenetics, histologic markers, and management options of this rare entity.

Benign metastasizing leiomyoma: clonality, telomere length and clinicopathologic analysis

“…In attempts to explain its dichotomous nature, several hypotheses have been proposed: first, it could be a benign uterine tumor that spreads via a hematogenous route to the lungs or other organs, as a majority of patients have undergone myomectomy or hysterectomy suggesting surgically induced hematogenous spread; second, it could be a low-grade leiomyosarcoma metastasizing to the lung; 2,4 and third, it could represent primary pulmonary leiomyomatosis unrelated to but coexisting with uterine leiomyomata. 15 Benign metastasizing leiomyoma is morphologically benign. Based on the H&E-stained sections, all eight tumors from three patients showed no evidence of high cellularity, cytological atypia, necrosis, or increased mitoses (Figure 2).…”

Benign Metastasizing Leiomyoma of the Lung

“…3,4) As most BML stain positive for estrogen and progesterone receptors, as in our case, hormone involvement in the progression of the lesions is likely. 3,9,10) In conclusion, BML is a borderline tumor with benign histologic features, in spite of its biological behavior suggesting malignancy. 1) Although it is a rare condition, it should be considered in asymptomatic women of reproductive age with a history of uterine leiomyoma, who present with solitary or multiple pulmonary nodules.…”

“…8,9) However, not all patients respond to hormone therapy, and side effects including flushes, fatigue, and nausea can be aggravating. 10) As our patient refused hormone treatment, a wait-and-see strategy was decided upon. The reason for tumor progression in BML is unclear.…”

Laparoscopic management of a pelvic retroperitoneal leiomyoma—case report

“…Several hypotheses have been proposed to explain the metastasizing theory (the lungs are the most common site of metastatic involvement): (1) it could be a benign uterine tumor that spreads via a hematogenous route to the lungs or other organs [25], (2) it could be a surgically induced hematogenous spread, and the tumor would gain venous access from surgical trauma during hysterectomy [26], and (3) it could be a low-grade metastatic leiomyosarcoma [27]. Retroperitoneal tumors are sometimes seen on autopsy or are detected incidentally on routine checkup; so, they could also represent primary extrauterine leiomyomatosis unrelated to but coexisting with uterine leiomyomata [28]. In our patient, it is difficult to believe in the iatrogenic or the residual parasitic theories because the previous hysterectomy was supracervical.…”