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Pooja Sharma



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    EP1.15 - Thymoma/Other Thoracic Malignancies (ID 205)

    • Event: WCLC 2019
    • Type: E-Poster Viewing in the Exhibit Hall
    • Track: Thymoma/Other Thoracic Malignancies
    • Presentations: 1
    • Now Available
    • Moderators:
    • Coordinates: 9/08/2019, 08:00 - 18:00, Exhibit Hall
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      EP1.15-19 - Primary Endobronchial Hyalinising Clear Cell Carcinoma Presenting in Association with Active Pulmonary Tuberculosis (Now Available) (ID 1619)

      08:00 - 18:00  |  Author(s): Pooja Sharma

      • Abstract
      • Slides

      Background

      Hyalinising clear cell carcinoma (HCCC) is a rare tumor of putative salivary gland origin that most commonly presents as an oral submucosal lesion in middle aged to elderly adults. With a characteristic histomorphology of infiltrating cords and nests of clear tumor cells set in a hyalinised stroma, these tumors frequently harbour EWSR1:ATF1 fusions, the latter serving as a useful diagnostic marker in differentiation from other clear cell-rich tumors. Only four cases with primary pulmonary origin have been previously reported, all of which were incidentally detected small (<3 cm) intrabronchial masses in non-smoking middle aged men. We report the fifth case in a 44-year-old non-smoker who presented with hemoptysis and was found to harbour a 3.5 cm intra-bronchial HCCC in association with active pulmonary and mediastinal tuberculosis.

      Method

      A 44-year-old male, non-smoker, presented with 2 episodes of hemoptysis. On imaging, a heterogeneously enhancing FDG-lobulated soft tissue mass was noted within the left lower lobe bronchus with lobar collapse. FDG avid nodular lesions were also seen in the left lower lobe parenchyma with enlarged aortopulmonary window and bilateral hilar lymphnodes. No pleural effusion was seen. There was no evidence of any metastatic lesions. He underwent an endobronchial biopsy from the left main bronchus followed by left lower lobectomy and mediastinal lymphadenectomy. Formalin fixed paraffin embedded tumor sections were subject to special stains for detection of acid fast bacilli and fungi, immunohistochemistry for p40, TTF-1, chromogranin, synaptophysin, epithelial membrane antigen, smooth muscle actin, S100 and smooth muscle myosin heavy chain, and fluorescence-in-situ hybridisation for 22q12 locus using the Vysis EWSR1 dual color, break apart rearrangement probe.

      Result

      Microscopic sections from the endobronchial biopsy revelaled a subepithelial tumor arranged in nests, cords and trabeculae within a densely hyalinised stroma. Tumor cells were monomorphic with clear to eosinophilic cytoplasm and occasional mitoses. Left lower lobectomy specimen showed a grossly circumscribed solid tumor in the wall of the left main bronchus abutting the cartilage and demarcated from adjacent lung parenchyma by a thin fibrous capsule. Tumor cells were immunopositive for p40, epithelial membrane antigen, while were negative for TTF-1, and myoepithelial markers. FISH revealed presence of EWSR1-re-arrangement in tumor cells, confirming the diagnosis of HCCC. Numerous mililary parenchymal and pleural nodules with necrotic caseous material containing acid fast bacilli were also seen, consistent with tuberculosis. Further work-up did not reveal presence of tumor elsewhere ascertaining a primary lung origin. Patient was started on anti-tubercular therapy and adjuvant radiotherapy/chemotherapy was not given. Patient is currently on follow-up

      Conclusion

      From the limited numbers reported, primary pulmonary HCCCs appear to be indolent slow growing neoplasms with an excellent outcome after surgical excision. The differential diagnoses include the commoner squamous cell carcinomas with clear cell change, clear cell adenocarcinomas, mucoepidermoid carcinomas, metastatic clear cell renal cell carcinoma, and myoepithelial neoplasms. Knowledge of its typical histomorphology aided by prudent immunohistochemistry and demonstration of EWSR1 gene rearrangement or more specifically, EWSR1:ATF1 fusion transcripts should lead one towards the correct diagnosis.

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