Osteosarcoma pleural effusion: A diagnostic challenge with some cytologic hints

Our plain-English summary of Osteosarcoma pleural effusion: A diagnostic challenge with some cytologic hints, by B. AbdullGaffar (Diagnostic Cytopathology, 2021).

The study

• Author: B. AbdullGaffar
• Journal: Diagnostic Cytopathology
• Published: 2021;49(1):E40-E44
• Type of article: Case report
• Cited by: 4 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Pleural effusions can be the first manifestation, recurrence, or metastasis of small round cell sarcomas in children. The most common are Ewing sarcoma, neuroblastoma, and rhabdomyosarcoma. The cytomorphology is variable, the cells can be cohesive, single cells, small or large, morphologically mimicking lymphomas, carcinomas, melanomas, and mesothelioma depending on the sarcoma involved. Osteosarcomas are rare. Their rarity, variable histomorphologic features, immunophenotypic heterogeneity, being of osseous or extraosseous origin and focality of malignant osteoid matrix make their cytologic recognition a diagnostic challenge. They can be confused with small round cell sarcomas, may be misinterpreted as degenerative inflammatory cells, or masked by florid reactive mesothelial hyperplasia particularly in pleural effusions. However, attention to certain cytomorphologic features in smears and cellblock sections should raise suspicion. We report a case of a 9-year-old child who presented with cough, chest pain and breathing difficulty, left pleural effusion, a collapsed consolidated lower lung lobe, and a clinical impression of pneumonia. Pleural fluid cytology was initially reported as inflammatory effusion with florid reactive mesothelial hyperplasia. Tissue biopsy of the lung mass showed histomorphologic features consistent with osteosarcoma. A careful look at the cytology materials and cellblock sections showed helpful cytomorphologic features that were masked by florid reactive mesothelial cells and misinterpreted as degenerative inflammatory lymphocytes. An extracellular matrix was a helpful hint. Malignant pleural effusion secondary to osteosarcoma is rare. Cytologic examination may help reach the correct diagnosis if the smears and cellblock sections are carefully evaluated for certain helpful cytomorphologic features, particularly osteoid matrix.

© 2020 Wiley Periodicals LLC.

In plain English

This brief report described one case: a 9-year-old child with β-thalassemia major, who had received radiation before a bone marrow transplant 3 years earlier, and who had cough, chest pain and breathing difficulty for 10 days. A chest X-ray showed a left pleural effusion and a collapsed lower lung lobe, and pneumonia was suspected. Pleural fluid cytology was first reported as inflammation with florid reactive mesothelial hyperplasia. When antibiotics did not work, a CT scan showed a 7.8 × 4.3 cm left lung mass involving the pleura. A biopsy was diagnosed as osteosarcoma after deeper sections showed malignant osteoid matrix. On re-review, the original fluid samples contained tumor cells that had been hidden among mesothelial cells or mistaken for degenerate inflammatory cells, plus occasional osteoid matrix. The author concluded that such effusions are rare and that careful review for these features, especially osteoid matrix, should help reach the diagnosis. The article does not concern asbestos. Mesothelioma is mentioned only as a tumor that other tumors can mimic in cell appearance and in immunostaining.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: case report (single patient)
• Who was studied: One 9-year-old child with β-thalassemia major who had a bone marrow transplant 3 years earlier. The author's pathology section is at Rashid Hospital, Dubai, United Arab Emirates.
• Exposure: No asbestos exposure is discussed. The patient had received radiation before the bone marrow transplant. The article does not link this to the tumor.
• Main results:
  • The pleural fluid cytology and cellblock were first reported as mixed inflammatory infiltrates with florid reactive mesothelial hyperplasia, consistent with parapneumonic effusion.
  • A CT scan showed a left lung mass measuring 7.8 × 4.3 cm that involved the pleura.
  • In the lung biopsy, the tumor cells were diffusely positive for vimentin and focally positive for CD99. Genetic studies did not show the fusion genes of Ewing sarcoma.
  • Deeper levels of the biopsy showed malignant osteoid matrix, and the final diagnosis was osteosarcoma.
  • On re-review, the conventional smears showed tumor cell clusters and single cells, with occasional foci of osteoid matrix.
  • The ThinPrep slide showed clustered abnormal cells but no osteoid matrix.
  • In the original review, single tumor cells had been misinterpreted as degenerate inflammatory lymphocytes.
• The authors' conclusion: The author concluded that malignant pleural effusions secondary to osteosarcoma are rare. In the author's view, careful evaluation of smears and cellblock sections for certain cell features, and especially for osteoid matrix, should help reach the correct diagnosis. In equivocal cases, immunohistochemical and molecular studies are helpful.
• Limitations the authors state:
  • Romanowsky-type stains (such as Giemsa and Diff-Quick), in which osteoid is more easily seen, could not be done retrospectively. The effusion fluid is routinely discarded a week after cytology reporting.

Topics

Medical terms in this study, explained in our Lexicon: Pleural Effusion, Metastasis, Sarcoma, Carcinoma, Mesothelioma, Reactive Mesothelial Hyperplasia, Fluid Cytology, Biopsy.

Related studies

• Extraskeletal osteosarcoma of the pleura:report of a case — H. Shiota, T. Yasukawa, et al. (2013)
• A left pleural effusion with a calcified tumoral mass and left hemithoracic uptake on bone scan — E. Quoix, M.P. Chenard, et al. (2001)
• Young investigator challenge: MicroRNA-21/MicroRNA-126 profiling as a novel tool for the diagnosis of malignant mesothelioma in pleural effusion cytology — R. Cappellesso, L. Nicolè, et al. (2016)
• The diagnostic utility of D2-40, calretinin, CK5/6, desmin and MOC-31 in the differentiation of mesothelioma from adenocarcinoma in pleural effusion cytology — T.S. Hyun, M. Barnes, et al. (2012)
• Evaluation of soluble mesothelin-related peptide as a diagnostic marker of malignant pleural mesothelioma effusions: its contribution to cytology — P.A. Canessa, M.C. Franceschini, et al. (2013)
• Diagnostic efficacy of electron microscopy and pleural effusion cytology for the distinction of pleural mesothelioma and lung adenocarcinoma — H. Domínguez-Malagón, A.M. Cano-Valdez, et al. (2016)

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