case_images: PMC8217822_01
case_images: (A) Left: MRI of right femoral head indicating metastasis diagnosis. Right: A partial response was achieved after radiotherapy and gefitinib treatment. (B) Left: Disease progression was found in mediastinal lymph nodes by CT. Right: A partial response was achieved after continued gefitinib treatment and radiotherapy. (C) Left: Metastasis was detected in the left adrenal gland. Right: CT image of the patient after left adrenalectomy was performed.
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case_images: PMC8217822_01_fonc-11-696881-g001.jpg
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case_images: Two years after the operation, metastasis in the right femoral head was detected by magnetic resonance imaging (MRI) ( Figure 1A ). Mediastinal lymphadenopathy was detected by CT in December 2017 ( Figure 1B ). Disease progression was revealed by CT showing a metastasis in the left adrenal gland in August 2020 ( Figure 1C ).
case_images: (A-C) Left adrenal gland specimen showing squamous cell carcinoma with negative staining for TTF-1 and partially positive staining for P40. (D-F) Resected lung sample showing adenocarcinoma with partial squamous differentiation, expressing focally positive TTF-1 and P40.
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case_images: PMC8217822_01_fonc-11-696881-g002.jpg
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case_images: TTF-1 and NapsinA negative, P40 partially positive, and CK7 positive ( Figures 2A-C ). The sample was subjected to a sequencing study using FoundationOne CDx (an FDA-approved 324-gene panel assay), and the results showed an EGFR exon 19 deletion (delE746_A750, allele frequency [AF]: 26.68%). Histopathological re-examination of the surgical sample from the resected primary lung carcinoma revealed adenocarcinoma with partial squamous differentiation (less than 5%), which was partially positive for TTF-1, NapsinA, and CK5/6, focally positive for P40, and CK7 positive ( Figures 2D-F ).
case_images: Timeline of the clinical course.
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case_images: PMC8217822_01_fonc-11-696881-g003.jpg
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case_images: The timeline illustrating this patient's medical history and treatment is presented in  Figure 3 .