A comprehensive review of the "tigroid" background cytological concept: what, when, where and why?

Cytomorphological Insights into Embryonal Rhabdomyosarcoma: A Rare Case in the Middle Ear

INTRODUCTION

Rhabdomyosarcoma, though rare in the middle ear, necessitates prompt recognition for optimal management. They are malignant mesenchymal neoplasms arising from the embryonic mesenchymal cells of striated skeletal muscles.

CASE PRESENTATION

We present a case of a 5-year-old child with massive right mastoid swelling and bloody ear discharge. Cytological examination via fine needle aspiration biopsy revealed features suggestive of a malignant mesenchymal tumor, confirmed on imaging and subsequent histopathology as embryonal rhabdomyosarcoma (ERMS) FNCLCC grade 2. Characteristic cytological findings included spindle-shaped cells in a myxoid stroma with tigroid background, aiding in early diagnosis. Despite radical mastoidectomy and adjuvant chemotherapy, ERMS in the middle ear remains challenging due to its aggressive nature and potential complications.

CONCLUSION

This case underscores the importance of cytological evaluation in identifying rare soft tissue tumors like ERMS, facilitating timely intervention and improved outcomes. Early recognition and multidisciplinary management are crucial in addressing the complexities of ERMS in uncommon sites like the middle ear.

CSF cytology of common primary CNS neoplasms categorized by CNS WHO 2021

OBJECTIVE

The detection of neoplastic cells in cerebral spinal fluid (CSF) is pivotal for the management of patients with central nervous system (CNS) tumours. This article delves into the CSF cytological characteristics of common CNS neoplasms, aligning with the 2021 World Health Organization (WHO) classification of CNS tumours.

METHODS

A retrospective review of CSF specimens positive for primary CNS neoplasms was performed at three tertiary medical centres. Only cases that had histopathologic confirmation and/or molecular workup were included.

RESULTS

Common primary CNS neoplasms seen in CSF cytology specimens include medulloblastoma, (non-WNT/non-SHH as well as SHH-activated and TP53 mutant), pineoblastoma, atypical teratoid/rhabdoid tumour (AT/RT), IDH-wildtype glioblastoma, and primary diffuse large B-cell lymphoma of the CNS. Ependymomas and germinomas can also have CSF involvement but are less common. Although the typical histologic architecture of these tumours may not be preserved in the CSF, unique cytomorphologic features such as nuclear moulding, nuclear pleomorphism, rhabdoid cells, prominent nucleoli and rosette formation can still be appreciated.

CONCLUSION

Adopting the updated terminology and correlating cytologic observations with molecular findings will streamline the diagnostic process, reducing the complexities and ambiguities pathologists often encounter when analysing CSF specimens for potential primary CNS neoplasms.

The Utility of Fine Needle Aspiration (FNA) Biopsy in the Diagnosis of Mediastinal Lesions

Fine needle aspiration is a minimally invasive, low-morbidity, and cost-efficient technique for the sampling of mediastinal lesions. Additionally, ancillary testing on FNA samples can be used for the refinement of diagnoses and for treatment-related purposes (flow cytometry, cytogenetics, immunohistochemistry, and molecular diagnostics). Mediastinal lesions, however, can show a variety of lineages and morphologic features, giving rise to diagnostic dilemmas. As a result, the differential diagnosis can vary widely and becomes especially challenging due to the smaller sample size on FNA and the variability in component sampling. For appropriate patient management and to determine the correct treatment strategies, accurate pathologic diagnoses are paramount. In this review, we present the cytomorphologic features together with the immunophenotypic findings of mediastinal lesions, with emphasis on the diagnostic challenges and pitfalls in FNA cytology samples, including smears and cell block sections.