Pulmonary Metastasizing Low-Grade Endometrial Stromal Sarcoma: Case Report and Review of Diagnostic Pitfalls

Abstract

Pulmonary manifestations of benign metastasizing leiomyoma (BML) usually include multiple well-defined, round, bilateral nodules. Low-grade endometrial stromal sarcoma (LG-ESS) is a rare uterine tumor. A 70-year-old woman visited the clinic complaining of acute cough and dyspnea in April 2017. Chest computed tomography (CT) revealed pneumothorax and multiple pulmonary nodules. She had a history of hysterectomy for uterine leiomyoma 23 years ago. Biopsy revealed that the pulmonary masses were consistent with BML. However, the patient had two subsequent episodes of acute, recurrent respiratory distress, accompanied by massive pleural effusions and hydropneumothorax over the next two years. A chest CT performed for acute dyspnea revealed large and multiple hydropneumothoraces. The size and distribution of pulmonary masses were aggravated along with cystic changes and bilateral pleural effusions. Given this aggressive feature, additional immunohistochemical findings and gynecologic pathologist review confirmed the correct diagnosis to be LG-ESS. After initiating anti-estrogen therapy, the patient achieved a partial response, without recurrence of symptoms, for 28 months. Metastatic LG-ESS responds well to anti-hormonal therapy. If the clinical pattern of a disease is different than expected, the possibility of a correction in the diagnosis should be considered.

Keywords: benign metastasizing leiomyoma; endometrial stromal tumor; letrozole.

Figure 1

A chest computed tomography (CT) features of the lung masses. A chest CT (April 2017) showed pneumothorax in the left lung and multiple masses in both lungs. The amount of pneumothorax was small (solid arrows) because CT was performed after the chest tube (dotted arrows) was inserted and stabilized.

Figure 2

Chest computed tomography (CT) features of the aggravating lesions. Cystic masses (arrow) and large and multiple hydropneumothoraces with massive pleural effusion (red circles) on chest CT (June 2019). (a) Coronal and (b) axial views.

Figure 3

Hematoxylin-eosin staining of the lung mass. Microscopic examination revealed metastatic lung nodules with small, uniform, and bland tumor cells with spindled nuclei and scant cytoplasm, in the background of rich small arterioles or capillary networks. (Magnification 200×).

Figure 4

Immunohistochemical staining of the lung mass. (A) Desmin is expressed in some tumor cells (200×), (B) h-Caldesmon is diffusely positive (200×). (C) Tumor cells reveal patchy cytoplasmic immunoreactivity on CD10 (200×). (D) Diffuse nuclear positivity of tumor cells with WT1 (200×).

Figure 5

Follow-up computed tomography examination. Follow-up chest computed tomography showed improved disease status (August 2021). (a) Coronal and (b) axial views.