Histopathologic review of 400 biopsies and resection specimens of trunk and extremity-based soft tissue tumors

Pitfalls in soft tissue cytopathology

Fine needle aspiration biopsy (FNAB) is a diagnostic modality for the evaluation of suspicious soft tissue masses. Despite its reasonable sensitivity, specificity and positive predictive value in differentiating benign from malignant neoplasms, the exact subtyping of the primary soft tissue tumours can be challenging. Certain tumours constitute "pitfalls" and add to the diagnostic challenge. This review provides a detailed account of the diagnostic challenges in soft tissue cytopathology, including pitfalls and, more importantly, the ways to overcome these challenges by integrating clinical details, key cytomorphological features and judicious application of ancillary techniques.

Cytomorphology of spindle cell/sclerosing rhabdomyosarcoma, including MYOD1 (LI22R) mutation result

Spindle cell/sclerosing rhabdomyosarcoma (RMS), characterized by MYOD1 (L122R) mutation in a subset of cases is a newly described subtype of RMS. Presently, there is no documentation of cytomorphological features, especially of sclerosing RMS. Case 1: A 24-year-old male presented with pain and swelling in his wrist for a one-year duration. MRI revealed a well-defined soft tissue lesion measuring 5.3 cm, encasing the lower end of the ulna. Fine-needle aspiration cytology (FNAC) smears revealed clusters of tumor cells with round to oval to spindle-shaped nuclei, scant to moderate amount of cytoplasm with the wisps of the metachromatic stroma. Histopathological examination revealed a malignant tumor comprising cells with polygonal to spindle-shaped nuclei, arranged in a sclerotic stroma. Immunohistochemically, the tumor cells were positive for desmin, myogenin, and MYOD1. A diagnosis of sclerosing RMS was offered. Furthermore, the tumor revealed MYOD1 (L122R) mutation. Case 2: A 43-year-old male presented with a 4-month history of "nasal stuffiness" and pressure. Imaging revealed a poorly defined infiltrative lesion in his nasal cavity. FNAC smears revealed loose and tightly cohesive clusters of malignant cells with oval to spindle-shaped nuclei, a moderate amount of ill-defined bluish to finely vacuolated cytoplasm, and focal streak artifact with interspersed stromal fragments. Histopathological examination revealed a malignant tumor composed of oval to spindle-shaped nuclei, embedded in a variably hyalinized stroma. Immunohistochemically, the tumor cells were positive for desmin, and myogenin. Diagnosis of spindle cell/sclerosing RMS was offered. The present study constitutes one of the first documentation of cytomorphological features of two rare cases of spindle cell/sclerosing RMS. The differential diagnoses and treatment-related implications are presented.

Resource-appropriate selection of osteosarcoma treatment protocols in low- and middle-income countries

Osteosarcoma is a rare malignancy; however, it is still the most common primary bone tumor in adolescents and young adults. Chemotherapy improves survival indubitably in osteosarcoma; nevertheless, the concern is the stagnant progress since the last several decades. There are a handful of active agents and unresolved issues, especially in choosing the ideal chemotherapy regimen. The oncology community is in equipoise regarding the position of high-dose methotrexate (HDMTX), mandatory or adjunct. The choice of therapy becomes widely relevant, including in low- and middle-income countries (LMIC), where HDMTX administration brings additional complexities. Research into novel non-HDMTX-based protocols adapted to the available resources is pivotal in improving disease outcomes, especially in LMIC. The current review focuses on real-world challenges in decision-making and provides a comprehensive overview of the evolution of treatment protocols in LMIC.

Adult Soft Tissue Sarcoma: A Prospective Observational Real-World Data

Introduction There is a lacuna of prospective studies on soft tissue sarcoma (STS) from the Indian subcontinent in published literature.

Objectives We conducted this study to describe the clinical profile and outcomes of STS in North India.

Materials and Methods This is a single-center, prospective, observational study conducted from October 2017 to September 2019. All consecutive patients aged ≥18 years with histopathological diagnosis of STS were enrolled. The study end points included overall response rate, progression-free survival (PFS), and overall survival (OS).

Results A total of 140 patients were included with a median duration of follow-up of 14 months (range: 1–25 months). The median age of patients was 45 years. The median duration of symptoms before diagnosis was 5 months (range: 1–18 months). The most common histopathologic subtype was undifferentiated pleomorphic STS (22%). Of 105 localized patients, 21 received neoadjuvant therapy with external beam radiotherapy and/or doxorubicin-based chemotherapy and reported partial response in 38% (8/21) of the patients; the remaining 62% (13/21) of the patients had stable disease. Neoadjuvant therapy resulted in nonsignificantly higher complete resection rates with relative risk of 2.37 (p = 0.19). Of the remaining 35 metastatic STS patients, 31 received chemotherapy and reported partial response in 39.1% (n = 9/23), stable disease in 30.4% (n = 7/23), and disease progression in 30.4% (n = 7/23) of the patients. For localized STS patients, 1-year disease-free survival (DFS) and OS rates were 87.6 ±3.5 and 95.3 ± 2.3%, respectively. The median OS for metastatic STS patients was 23.90 months (95% confidence interval [CI]: 7.43–40.36). Among metastatic STS, median OS was not reached for those who underwent curative resection versus 12.66 months (95% CI: 9.28–16.04) for those who received systemic therapy alone.

Conclusion Median age of 45 years is a decade earlier than seen in the Western population. Neoadjuvant therapy improved complete resection rates, though it was statistically nonsignificant. Curative resection among metastatic STS patients improves survival.

Revisiting cytomorphology, including unusual features and clinical scenarios of 8 cases of alveolar soft part sarcoma with TFE3 immunohistochemical staining in 7 cases

OBJECTIVES

To present a comprehensive analysis of cytomorphological features, including clinical scenarios, for 8 cases (4 males, 4 females, aged 17-39 years, average = 28.5) of, retrospectively diagnosed alveolar soft part sarcoma (ASPS), with TFE3 immunostaining in 7 cases.

METHODS

Conventional Papanicolaou and May Grunwald-Giemsa (MGG) stained smears and corresponding tissue sections were critically reviewed. Fine needle aspiration cytology was performed for primary diagnosis in 6 cases and for metastatic lesions in 2 cases. TFE3 and other immunohistochemical stains were tested using polymer detection technique.

RESULTS

Tumour sites were thigh (n = 6), shoulder (1) and neck (1). Tumour size (n = 6) varied from 5 to 14.5 cm (average = 7.2). Seven out of 8 cases were correctly diagnosed on cytosmears. The smears were mostly hypercellular (5), composed of cohesive clusters (8), including cell balls and pseudopapillae (3) and singly scattered cells (8). Tumour cells were round to oval, containing central to eccentric nuclei (8), abundant granular (8) to finely vacuolated (7) cytoplasm that was ill- to well-defined, intracytoplasmic rod-like or needle-shaped crystals (3) and prominent nucleoli (8), Additionally, there were binucleated cells (7), multinucleation (2), intracytoplasmic inclusions (3), intranuclear inclusions (2), intercellular stroma (5) and bare nuclei (8). Immunohistochemically, 7/8 tumours were positive for TFE3.

CONCLUSIONS

This constitutes the largest series describing cytomorphological spectrum of ASPS with TFE3 immunostaining results. Frequently observed features and rod-like/needle-shaped crystals on MGG smears, can help to differentiate ASPS from its mimics. TFE3 immunostaining aids in substantiating diagnoses, in an appropriate clinicoradiological context.

Core Needle Biopsy versus Fine Needle Aspiration Cytology in Bone and Soft Tissue Tumors

Fine needle aspiration cytology (FNAC) for diagnosis of musculoskeletal tumors is well discussed and debated. The current evidence restricts its application in recurrent and metastatic lesions, with core needle biopsy as the acceptable technique/gold standard for the primary diagnosis of these challenging tumors. However, there are several studies showing reasonable sensitivity and specificity in primary diagnosis of bone and soft tissue tumors, especially in differentiating benign from malignant tumors. There is an acceptable limitation in the exact subtyping of soft tissue tumors, based on cytology smear examination, in the absence of ancillary techniques. Nonetheless, cytology constitutes an optimal material for triaging cases for ancillary techniques, such as immunocytochemistry, immunohistochemistry, molecular cytogenetics, and molecular diagnosis, in the form of smears and cell block preparations. This review focuses on the strengths and limitations of cytology versus core needle biopsy in the diagnosis of bone and soft tissue tumors, with the current evidence in the form of published studies, including the authors' experience.