Unusual lesions of the mediastinum

Our plain-English summary of Unusual lesions of the mediastinum, by F. Shamsuddin, U.N. Khadilkar, D. Saha (Lung India, 2015).

The study

• Authors: F. Shamsuddin, U.N. Khadilkar, D. Saha
• Journal: Lung India
• Published: 2015;32(6):566-71
• Cited by: 3 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Objectives: To study unusual lesions in the mediastinum, which do not originate from the thymus, lymph nodes, neural tissues or germ cells, and tissues that normally engender pathologic lesions in the mediastinum.

Materials And Methods: Of the 65 cases seen, 12 unusual lesion were encountered in a 5½ year period from 2006 to 2011.

Results: Two cases of nodular colloid goiter and one each of the mediastinal cyst, undifferentiated carcinoma, and Langerhans cell histiocytosis (LCH) affected the anterosuperior mediastinum. In the middle mediastinum, one case each of the mesothelioma, malignant gastrointestinal stromal tumor (GIST), squamous cell carcinoma (SCC), solitary fibrous tumor (SFT), and pleomorphic sarcoma (PS) was seen. One case of meningeal melanocytoma (Mme) and primary pleural liposarcoma (PL) involved the posterior mediastinum. Persistent disease was seen in LCH after 2 years. Of all the cases with malignant lesions, only the patient with SCC was alive after 1 year.

Conclusion: The cases of primary and SCC, LCH, melanocytoma, liposarcoma and PS, and GIST are unexpected and very rarely have paradigms in the mediastinum. Radiologic impression and knowledge of the compartment where these lesions arose from hardly assisted in arriving at a definitive opinion as the lesions were not typical of this location. A high index of suspicion and the immunohistochemical profile facilitated the final diagnosis.

In plain English

This article was a case series from the Department of Pathology at Kasturba Medical College, Mangalore, India. Between January 2006 and June 2011, 65 mediastinal lesions were seen. The authors described 12 of these lesions as unusual because they did not come from the tissues that usually cause lesions in the mediastinum. The 12 included two goiters, a cyst, a case of Langerhans cell histiocytosis, carcinomas, sarcomas, a solitary fibrous tumor, a melanocytoma, a malignant gastrointestinal stromal tumor that had spread to the mediastinum from the small intestine, and one malignant mesothelioma. The mesothelioma was a sarcomatoid variant in the middle mediastinum. It was found in a resected mass measuring 18 cm in a 21-year-old man and was staged T3. The authors noted that his occupational history was missing, and the article gives no information on asbestos exposure for him. Patients were aged 1½ to 65 years. Radiology generally did not provide the diagnosis. Several patients with malignant tumors died within one to three months. The authors concluded that a high index of suspicion and immunohistochemical testing helped reach the final diagnoses.

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 series from a single hospital pathology department (descriptive review of 12 unusual mediastinal lesions)
• Who was studied: 12 patients with unusual mediastinal lesions, out of 65 mediastinal cases seen at the Department of Pathology, Kasturba Medical College, Mangalore, Karnataka, India, January 2006 to June 2011. Ages ranged from 1½ to 65 years, and the male to female ratio was 2:1.
• Exposure: No exposure was studied. For the single mesothelioma case, the authors stated that the patient's occupational history was missing. Asbestos figures in the discussion come from other cited studies, not from this study.
• Main results:
  • 12 of 65 mediastinal cases seen over 5½ years were classed as unusual lesions.
  • The mesothelioma was one of the lesions in the middle mediastinum.
  • One malignant mesothelioma (sarcomatoid variant) was diagnosed in a 21-year-old man. It was a resected mass measuring 18 cm by 10 cm by 6 cm with variegated and necrotic areas.
  • The mesothelioma tissue was positive for calretinin and cytokeratin on immunohistochemistry.
  • The mediastinal involvement of the mesothelioma was WHO stage T3.
  • The gastrointestinal stromal tumor was a metastatic malignant epithelioid GIST in the mediastinum. An earlier small intestinal mass had shown similar morphology.
  • The patients with mesothelioma and with pleomorphic sarcoma had pleural effusion without any diagnostic cells.
  • In most of these tumors, radiology did not provide the diagnosis or show whether the lesion was benign or malignant.
  • Outcomes in individual patients: the patient with poorly differentiated carcinoma died within 3 months; the patient with metastatic GIST died 1 month later; both sarcoma patients had died at 3 months; the squamous cell carcinoma patient was alive at 1 year; the solitary fibrous tumor patient was alive without disease at 1 year. The mesothelioma patient's outcome is not given in the article body.
  • The child with Langerhans cell histiocytosis (18 months old) still had hepatosplenomegaly at 2 years of follow-up after three cycles of chemotherapy.
• The authors' conclusion: The authors concluded that these 12 lesions were widely diverse, that radiology and knowledge of the mediastinal compartment were of little help, and that a high index of suspicion and immunohistochemistry played a substantial role in the final diagnosis. They also noted that most of the unexpected malignant lesions had a bad prognosis.
• Limitations the authors state:
  • No occupational history was available for the mesothelioma patient.
  • CD1a, which the authors call the definitive stain for Langerhans cell histiocytosis, was not available, so S100 was used instead.
  • The mediastinal cyst's origin could not be investigated further.

Topics

Medical terms in this study, explained in our Lexicon: Mediastinum, Carcinoma, Mesothelioma, Squamous Cell Carcinoma, Solitary Fibrous Tumor, Pleomorphic, Sarcoma.

Related studies

• An unusual isolated anterior mediastinal lesion — N. Quigley, L. Lang-Lazdunski, et al. (2022)
• Solitary fibrous tumor of the mediastinum. A report of 14 cases — G.B. Witkin, J. Rosai (1989)
• A biphasic tumor of the mediastinum with features of synovial sarcoma. A report of four cases — G.B. Witkin, M. Miettinen, et al. (1989)
• Solitary fibrous tumor of the mediastinum — N. Weidner (1991)
• Calcifying fibrous pseudotumor of mediastinum--a case report — H.S. Jeong, G.K. Lee, et al. (1997)
• The Framingham Heart Study: Populational CT-based phenotyping in the lungs and mediastinum — T. Araki, G.R. Washko, et al. (2020)

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