Metastatic leiomyosarcoma of the uterus with heterologous differentiation to malignant mesenchymoma

A case report of recurrent leiomyosarcoma with chondrosarcoma differentiation in the abdominal wall and a review of the literature

Leiomyosarcoma with heterologous differentiation is relatively rare. To date, only 19 cases have been reported in the English literature. Heterologous components frequently show histological pleomorphism, while those exhibiting well-differentiated morphology are seldom reported. Here, we report a 34-year-old female diagnosed with leiomyosarcoma and developed abdominal wall recurrence 8 years after primary surgery. The recurrent tumor mainly comprised well-differentiated chondrosarcoma except a single focus of leiomyosarcoma. Due to the rarity and prolonged onset of such a transition, our case provides insight into the understanding of this phenomenon.

Metastatic Uterine Leiomyosarcoma With Rhabdomyosarcomatous Heterologous Differentiation

Heterologous differentiation has only been previously reported twice in metastatic uterine leiomyosarcomas. We report herein the first case of metastatic uterine leiomyosarcoma with rhabdomyosarcomatous differentiation. A 67-yr-old woman presented with femur, abductor magnus, and lymph node metastases 9 yr after the primary diagnosis. The metastatic sites showed rhabdomyosarcomatous morphologic features, and immunohistochemical studies confirmed skeletal muscle differentiation. Molecular testing revealed the same loss-of-function TP53 mutation in the uterine leiomyosarcoma and metastatic sites supporting heterologous differentiation of the primary tumor. Our case highlights the morphologic shifts metastatic tumors may manifest and the potential diagnostic problems that may arise.

"Malignant Mesenchymoma" Revisited: A Clinicopathologic Study of Leiomyosarcomas With Osteosarcomatous Differentiation

Leiomyosarcoma (LMS) is the most common sarcoma in adults. Rarely, LMS dedifferentiates into an undifferentiated sarcoma. Very few cases of LMS with heterologous osteosarcomatous differentiation (OS) have been reported. The purpose of this study was to evaluate the clinicopathologic features of LMS with OS. Of 5570 LMS cases diagnosed from 2006 to 2022, 15 cases (0.2%) of LMS with OS were identified, affecting 13 females and 2 males; ages ranged from 32 to 66 years (median: 53 y). Ten tumors arose in the uterus, 2 in the retroperitoneum, and 1 each in the mesentery, mediastinum, and rectum. Primary tumors ranged from 7 to 20 cm (mean: 16 cm). The LMS components showed conventional spindle cell morphology in most cases; 3 cases showed marked pleomorphism; 3 cases contained an epithelioid component; and 1 case showed myxoid features. In 5 cases OS was identified in the primary tumor, whereas in 10 cases OS was first detected in metastases. One metastatic and 2 primary LMS showed both OS and chondrosarcomatous differentiation. Prominent osteoclastic giant cells were seen in the OS components in 11 cases. Mitotic activity ranged from 17 to 61/10 HPF with tumor necrosis in 10 cases. Twelve patients developed metastases; sites included lungs, diaphragm, kidney, adrenal glands, colon, small intestine, liver, bone, and pancreas. At last follow-up, 8 patients had died of disease, and 4 patients were alive with metastases. The interval between OS and death ranged from 3 weeks to 18 months (median: 6.5 mo). Development of OS in LMS is exceptionally rare. This form of heterologous differentiation may occur in both primary tumors and metastases. LMS with OS is highly aggressive with poor outcomes. Awareness of this phenomenon is important to avoid misdiagnosis as osteosarcoma.

Uterine leiomyosarcoma with osteoclast-like giant cells associated with high expression of receptor activator of nuclear factor κB ligand

The occurrence of osteoclast-like giant cells (OLGCs) in uterine leiomyosarcomas (LMSs) is a rare phenomenon. The nature of OLGCs and the significance of their accumulation in these tumors are poorly understood. Recent studies revealed that the formation of osteoclasts requires a specific cytokine, receptor activator of nuclear factor κB ligand (RANKL), in bone. In this study, we investigated the expression of RANKL in 2 cases of uterine LMS with OLGCs by means of immunohistochemistry and compared the extent of RANKL expression with that in conventional uterine LMSs and leiomyomas by using real-time reverse-transcription quantitative polymerase chain reaction. Our cases of uterine LMS with OLGCs showed markedly high expression of RANKL messenger RNA with clear RANKL immunoreactivity compared with messenger RNA expression and immunoreactivity of conventional uterine LMSs and leiomyomas. These findings suggest that the tumors producing RANKL may account for accumulation of OLGCs in tumor tissue because of RANKL-related osteoclastogenesis.

Molecular Analysis of a Recurrent Sarcoma Identifies a Mutation in FAF1

A patient presented with a recurrent sarcoma (diagnosed as leiomyosarcoma) 12 years after the removal of an initial cancer (diagnosed as extracompartmental osteosarcoma) distally on the same limb. Following surgery, the sarcoma and unaffected muscle and bone were subjected to measurements of DNA exome sequence, RNA and protein expression, and transcription factor binding. The investigation provided corroboration of the diagnosis leiomyosarcoma, as the major upregulations in this tumor comprise muscle-specific gene products and calcium-regulating molecules (calcium is an important second messenger in smooth muscle cells). A likely culprit for the disease is the point mutation S181G in FAF1, which may cause a loss of apoptotic function consecutive to transforming DNA damage. The RNA levels of genes for drug transport and metabolism were extensively skewed in the tumor tissue as compared to muscle and bone. The results suggest that the tumor represents a recurrence of a dormant metastasis from an originally misdiagnosed neoplasm. A loss of FAF1 function could cause constitutive WNT pathway activity (consistent with the downstream inductions of IGF2BP1 and E2F1 in this cancer). While the study has informed on drug transport and drug metabolism pharmacogenetics, it has fallen short of identifying a suitable target for molecular therapy.

Dedifferentiated leiomyosarcoma of the uterus with heterologous elements: a potential diagnostic pitfall

Dedifferentiation is a phenomenon that is well characterized in a variety of tumors and is defined by the occurrence of a high-grade or undifferentiated tumor, typically unrecognizable regarding its line of differentiation, from a low-grade/borderline neoplasm. This phenomenon has previously been described in 2 uterine leiomyosarcomas, but both were devoid of heterologous elements. The authors describe herein a case of a dedifferentiated leiomyosarcoma of the uterus with osteoid heterologous elements, believed to be the first such reported case. The original tumor was a high-grade leiomyosarcoma with large low-grade and leiomyoma-like areas and whose constituent cells displayed intense nuclear immunoreactivity for both estrogen receptor (ER) and progesterone receptor (PR) in approximately 30% of cells. The tumor recurred six months after its resection as an undifferentiated sarcoma that was negative for smooth muscle markers, but which remained positive for ER and PR. Osteoid production was only identified in the recurrent tumor and was significant in extent therein. This case highlights the immunophenotypic changes that may occur in dedifferentiated leiomyosarcomas, and this possibility should be a consideration when an apparently undifferentiated sarcoma is identified in a patient with a history of uterine leiomyosarcoma. In our case, the expression of ER and PR provided significant supportive evidence of the uterine origin of the recurrent tumor.