Delayed osseous metastasis from low‐grade endometrial stromal sarcoma: Uncommon occurrence deserving recognition

Abstract Despite excellent prognosis, low‐grade endometrial stromal sarcoma (ESS) is notorious for late recurrence even in stage I disease. Bone metastases are distinctly rare and only six cases have so far been reported. Two patients presented with back pain due to spinal metastatic low‐grade ESS after 15 and 9 years free of disease after resection of the stage 1 primary uterine tumor. Plain radiograph showed an ivory first lumbar vertebra in the first patient and an osteolytic lesion involving the second thoracic vertebra in the second. In both cases, magnetic resonance imaging showed vertebral tumor with intra‐spinal extension and spinal cord compression; biopsy confirmed the diagnosis of metastatic low‐grade ESS. The first patient received palliative radiotherapy and chemotherapy while the second underwent surgical decompression followed by adjuvant radiotherapy and chemotherapy. The neurologic symptoms in both patients returned 12 months afterwards and progressed relentlessly despite adjuvant chemotherapy and radiotherapy. The first patient developed multiple bone and lung metastasis, culminating in death 44 months after recurrence. While surviving at 24 months from recurrent disease, the second became paraplegic with double incontinence and was wheelchair bound. Delayed osseous metastatic low‐grade ESS, although uncommon, deserves recognition given the predilection for spine as the site of involvement. In such a location, where complete surgical removal is notoriously difficult, if not impossible, the prognosis of spinal metastatic low‐grade ESS appears grave with considerable morbidity and mortality.