Diagnostic challenge between placental transmogrification and low-grade endometrial stromal sarcoma metastases in a patient with cavitary pulmonary nodules

Cystic lung lesions have limited differential diagnosis, which includes pulmonary Langerhans cell histiocytosis (LCH), lymphangioleiomyomatosis (LAM), lymphocytic interstitial pneumonitis (LIP), tracheobronchial papillomatosis, and Birt-Hogg-Dube syndrome. However, a few rare entities such as pulmonary placental transmogrification (PPT) and metastatic endometrial stromal cell sarcoma (ESS) also can present as cystic lung lesions and pose diagnostic challenges to both radiologists and pathologists. Clinical history is the key in such situations. Since the first description in the literature of these both entities, there have been very few cases reported. We present our case in a middle-aged female who was known to have cystic lung disease but treated as LAM and had a recurrent pneumothorax. Surgical pathology ruled out LAM and other interstitial cystic lung diseases and provided a diagnosis of PPT on wedge resection. Subsequent recurrence of cystic lung nodules led to the re-examination of histopathology and immunohistochemistry, concluding a diagnosis of metastasis from remote but undiagnosed low-grade stromal cell sarcoma. We will discuss the clinical, imaging and pathologic features of both of the diagnoses in this report. Institutional review board approval was not required since it was a single patient report.