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

Soft Tissue Fine-Needle Aspiration: Current and Future Impact on Patient Care

Soft tissue neoplasms pose many diagnostic challenges on fine-needle aspiration (FNA), owing largely to their rarity, large number of entities, and histologic diversity. Advances in ancillary testing now allow detection of the characteristic immunophenotypes and molecular alterations for many neoplasms and include reliable surrogate immunohistochemical markers for underlying molecular events that are highly efficient in small biopsies. A morphology-based framework is recommended to guide appropriate differentials and judicious selection of ancillary tests for small biopsies. The accurate diagnosis of soft tissue tumors is crucial for patient management and prognostication, with many potential implications in this era of precision medicine.

Fine-needle aspiration cytology of retroperitoneal myoepithelial carcinoma: A rare encounter with diagnostic dilemmas

Myoepithelial carcinoma (MC) arises from the myoepithelial cells. It is a rare tumor with a predilection for salivary glands. MC in soft tissue is uncommon. Soft tissue MC exhibits dual epithelial and smooth muscle phenotype. The extremities and limb girdles are commonly affected. We present cytological findings of retroperitoneal MC with an accurate diagnosis being rendered with the aid of immunocytochemistry on the cell block and demonstration of EWSR1 rearrangements by fluorescence in situ hybridization on cytology smear. The smears were cellular, showing loose clusters and sheets of tumor cells embedded in dense eosinophilic to myxoid matrix material. The cells were oval to polygonal, with focal areas showing moderate nuclear pleomorphism, vesicular to coarse chromatin, and vacuolated cytoplasm with clearing. On immunocytochemistry, tumor cells were positive for epithelial membrane antigen, pan-cytokeratin, calponin, smooth muscle actin, and S-100. A literature review shows only a handful of cases of soft tissue MC. The current report emphasizes the need for cytomorphological awareness with the employment of ancillary testing for accurately diagnosing this rare tumor at an uncommon location. We also discuss the diagnostic challenges and troubleshooting.

SMARCB1/INI1-deficient intrathoracic neoplasm with rhabdoid/plasmacytoid cytomorphology in a patient with plasma cell myeloma: A case report

SMARCB1 (INI1) is one of the switch/sucrose nonfermentable (SWI/SNF) complexes whose loss is associated with several tumors. SMARCB1 (INI1)-deficient intrathoracic neoplasms are extremely rare and known to be highly malignant and lethal. This report presents the case of a patient diagnosed with SMARCB1 (INI1)-deficient intrathoracic neoplasm during chemotherapy for plasma cell myeloma. A 77-year-old male patient complained of cough, bloody sputum, and fever with an enlarged right lung mass and pleural effusion. His cytological examination revealed undifferentiated epithelioid and rhabdoid/plasmacytoid cells with bi- or multinucleation, vacuolization, mitosis, and pleomorphism. However, it was difficult to distinguish the relapse of plasma cell myeloma as atypical plasmacytoid cells were detected. Immunohistochemically, the neoplastic cells showed a loss of SMARCB1 (INI1) expression in the cell block of pleural fluid and in the right lung of the autopsy specimen. Further, the patient was diagnosed with SMARCB1 (INI1)-deficient intrathoracic neoplasm of the right lung based on histological and autopsy findings. To the best of our knowledge, this is the first report of cytomorphology in a SMARCB1 (INI1)-deficient intrathoracic neoplasm.

Extraskeletal myxoid chondrosarcoma of the gingival: a rare case report and review of the literature

BACKGROUND

Extraskeletal myxoid chondrosarcoma (EMC) is a rare malignant tumor described in the head and neck region, especially in the gingival. We present one case arising in the gingival of right mandible, and briefly reviewed the related literature.

CASE PRESENTATION

A 24-year-old male patient with a lesion of 3.5*2.0 cm in buccal gingival of right posterior mandible for 2 months. The tumor was composed of cartilaginous structures and myxoid matrix. Immunohistochemical(IHC) showed that the tumor cells to be positive for vimentin, focally positive for S-100, negative for calponin, SMA, SOX10. The Ki-67 labelling index was 80%. Fluorescent in situ Hybridization (FISH) was positive for NR4A3 rearrangement.

CONCLUSIONS

Due to its unusual site and low incidence in the oral region, a combination of histological findings, immunohistochemistry, and molecular pathology as well as differential diagnosis with other diseases should be taken into consideration in the process of clinical diagnosis and treatment.

Commentary on: SMARCB1 as a novel diagnostic and prognostic biomarker for osteosarcoma

In the last couple of decades, biomarkers have been on the rise for diagnostic and predictive value. There has been a rush to identify new markers using new technologies and drug repurposing approaches. SMARCB1 acronym arises from the SWI/SNF (SWItch/Sucrose Non-Fermentable)-related Matrix-associated Actin-dependent Regulator of Chromatin subfamily B member 1 (SMARCB1). It is a molecule, whose role is associated with the sucrose metabolism. SMARCB1 is also called INI1 (Integrase Interactor 1). The molecule was discovered in the mid-1990s. Its role as a loss-of-function marker for malignant rhabdoid tumors (MRT) of renal and extrarenal origin has enormously expanded the spectrum of involved neoplasms since that time. Several tumors have been characterized by genetic aberrations in the SMARCB1 gene. They include reduction in expression, loss of expression, and mosaic expression. Most of the tumors are sarcomas, but a variegated group of tumors with mixed phenotypes has also been delineated. It is well known that the outcome of patients harboring genetic aberrations in the SMARCB1 gene has been poor. Guo et al. reported that reduced SMARCB1 expression occurred in 70% of osteosarcomas. Their data significantly correlated with poor neoadjuvant response. These authors emphasize a shorter progression-free and overall survival of the patients demonstrating an altered expression of this gene. Interestingly, mRNA in silico analysis established that SMARCB1 expression correlates with the response to chemotherapy of osteosarcoma patients, but there was no reliable correlation between SMARCB1 expression level and metastasis, response to neoadjuvant therapy, overall survival, and progression-free survival. The study involved a tissue microarray (TMA) on bone tumors that may limit the full evaluation of the gene expression. Nevertheless, Guo et al.’s study is remarkable. It expands the list of the tumors harboring an altered SMARCB1 gene expression and suggests that this marker should be investigated in every pathology workup for potential predictive value. On the other side, much work needs to be done if we hope that we strive to provide additional therapeutic strategies for osteosarcoma patients with altered SMARCB1 gene expression.