Rhabdomyosarcoma with epithelioid morphology: A challenging cytologic diagnosis in a pleural effusion

Epithelioid and spindle rhabdomyosarcoma with TFCP2 rearrangement in abdominal wall: a distinctive entity with poor prognosis

BACKGROUND

Epithelioid and spindle rhabdomyosarcoma (ES-RMS) with TFCP2 rearrangement is a recently discovered rare variant of rhabdomyosarcoma composed of epithelioid and spindle cells, because it shows extraordinarily adverse prognosis and is easily misdiagnosed as other epithelioid or spindle cell tumors.

METHODS

A rare case of ES-RMS with TFCP2 rearrangement was presented and English literatures in Pubmed online up to 01 July 2022 were gathered by two authors for a systematic review according to the inclusion and exclusion criteria.

CASE PRESENTATION/RESULTS

We report a case of ES-RMS in an early 30s-years-old female, the neoplastic cells are remarkably immunoreactive with CK(AE1/AE3), and partially with ALK protein. Unexpectedly, the tumor shows TFCP2 rearrangement with coexistence of increased copy numbers of EWSR1 and ROS1 gene and MET gene mutation. Besides, Next-generation sequencing for genetic mutational profiling revealed frequent MET exon14 mutations in chromosome 7, most of which are C > T nonsynonymous SNV, and exon42 of ROS1 in chromosome 6 showed frequent G > T mutation up to 57.54%. In addition, neither MyoD1 mutation nor gene fusions were detected. Moreover, the patient shows high tumor mutational burden (TMB) up to 14.11 counts/Mb. Finally, as many cases of ES-RMS including our case had local progression or metastasis, we find, similar to epithelioid rhabdomyosarcoma (median survival time is 10 month), ES-RMS shows a more aggressive behavior and adverse prognosis (median survival time is 17 month) than spindle cell/sclerosing rhabdomyosarcoma (median survival time is 65 month) according previous studies.

CONCLUSIONS

ES-RMS with TFCP2 rearrangement is a rare malignant tumor and easily confused with other epithelioid or spindle cell tumors, it may harbor additional gene alteration in addition to TFCP2 rearrangement, such as MET mutation, increased copy numbers of EWSR1 and ROS1 gene, high TMB. Most importantly, it may show very poor outcome with extensive metastasis.

Metastatic sarcomas to pleural effusion: a 10-year large tertiary care center experience with emphasis on clinical features and cytomorphologic characteristics

INTRODUCTION

Metastatic sarcomas to pleural effusion are extremely rare, accounting for <1% of all malignant pleural effusions. We aim to present our experience with pleural effusion specimens containing metastatic sarcomas over a 10-year period.

METHODS

We performed a 10-year retrospective search of cytopathology archives to identify all pleural effusions that were involved by metastatic sarcoma. All available cytopathology and surgical pathology specimens were retrieved and reviewed.

RESULTS

Twenty-eight pleural fluids from 22 patients with metastatic sarcoma were identified in our search. The patients' ages ranged from 12 to 73 years. The pleural fluid volumes ranged from 10 to 1500 ml. Rhabdomyosarcoma was the most commonly encountered metastatic sarcoma to pleural effusion (n = 7). Other metastatic sarcomas were as follows: epithelioid angiosarcoma (n = 4), Ewing sarcoma (n = 3), clear cell sarcoma (n = 2), high grade conventional osteosarcoma (n = 2), undifferentiated pleomorphic sarcoma (n = 1), epithelioid sarcoma, proximal type (n = 1), dedifferentiated liposarcoma (n = 1), and conventional chondrosarcoma (n = 1). The time between initial diagnosis and effusion varied from 3 months to 25 years. Two patients are alive with disease at 6 and 21 months of follow-up. All other patients were dead of disease and the survival after a malignant pleural effusion ranged from <1 month to 18 months.

CONCLUSIONS

Metastatic bone and soft tissue sarcomas to pleural effusions are rare and their cytologic features can be mistaken for carcinoma, melanoma, or mesothelioma. Careful review of the patient's medical history, comparison of the previous pathology and the use of ancillary studies are crucial for the evaluation of pleural effusions involved by metastatic sarcomas.

Myoepithelial carcinoma of soft tissue is a diagnostic challenge on fine-needle aspiration: Case report and review of literature

Myoepithelial carcinoma (MEC) of soft tissue, also known as malignant myoepithelial tumor, is an uncommon malignancy. Cytologic diagnosis of this entity is challenging due to its rarity and heterogeneous morphology. We report a case of MEC in a 22-year-old man, who presented with a 6.5 cm soft tissue mass on his right distal forearm that has been enlarging over the past 3 months. Ultrasound-guided fine-needle aspiration (FNA) revealed abundant isolated neoplastic cells ranging from spindled cells to epithelioid and plasmacytoid morphology in a myxoid background. These cells showed moderate cytologic atypia characterized by high-nuclear/cytoplasmic ratio, irregular nuclear contours, and prominent nucleoli. The cytoplasm varied from dense to vacuolated and occasionally rhabdoid with intracytoplasmic inclusions. Scattered bi- and multinucleated cells were identified. A diagnosis of high-grade malignancy was made with the differential diagnosis including rhabdomyosarcoma and melanoma. A subsequent core biopsy of the tumor showed immunoreactivity for pan-cytokeratins, calponin, p63, and smooth muscle actin. INI-1 was lost. SOX-10 and Melan-A were negative. Molecular studies showed loss of SMARCB1 (INI-1) and CDKN2A. Gene fusion studies did not detect any fusion. A diagnosis of soft tissue MEC was made which is a challenge on FNA due to several cytologic mimickers including rhabdomyosarcoma, epithelioid sarcoma, extrarenal rhabdoid tumor, extra-axial chordoma and melanoma. Recognition of the biphasic cell population in a myxoid background and a battery of immunohistochemical stains are crucial for accurate diagnosis.