PMC8497148_01
An endoscopic examination of the pharynx showed an irregularly elevated lesion at the base of the tongue.
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An endoscopic examination of the pharynx showed an irregularly elevated lesion on the base of the tongue (Figure 1).
(a) Neck CT showed a tumor at the base of the tongue and left cervical lymph node metastasis. (b) Chest CT showed a nodule in the right inferior lobe of the lung and a postoperative scar lesion derived from breast cancer on the right chest wall. (c) PET-CT showed marked glucose uptake by the base of the tongue (maximum standardized uptake value (SUV max) early: 16.35, delayed: 17.90), the left cervical lymph nodes (SUV max early: 15~17, delayed: 17~19), (d) the scar on the right chest wall (SUV max early: 3.47, delayed: 3.19), and the nodule in the right lung (SUV max early: 2.09, delayed: 2.42). (e) There was no other apparent distant metastasis. (f, g) Neck MRI T1-weighted imaging (WI) and T2WI showed that the tumor at the base of the tongue and the left cervical lymph nodes exhibited slightly higher intensity than the surrounding muscles.
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Right lung metastasis was observed on chest computed tomography (CT) and positron emission tomography- (PET-) CT (Figure 2), and HPV-positive poorly differentiated squamous cell carcinoma of the oropharyngeal anterior wall (T2N1M1 stage IV) was diagnosed.
At 6 months after treatment, PET-CT no longer showed increased glucose uptake by the lesions.
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PET-CT performed after 6 months' treatment showed that the primary lesion in the oropharynx, the metastasis to the neck, and the pulmonary metastasis had disappeared (Figure 3).
At 20 months after treatment, (a) an endoscopic examination of the pharynx showed that there was no recurrence at the base of the tongue. (b) Lumbar MRI T1W1 showed a metastatic lesion in the L4 vertebra. (c) PET-CT showed multiple metastases in the bilateral lungs, right hilum, right axillary lymph nodes, and some bones.
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Metastasis to the fourth lumbar vertebra and worsening of the pulmonary metastasis were seen on lumbar magnetic resonance imaging (MRI) and PET-CT performed 20 months after the chemoradiotherapy (Figure 4).
The microscopic findings of the resected L4 bone marrow (A) and pharyngeal tumor (a) are shown. HE staining did not reveal melanotic granules in the malignant cells of either lesion. Proliferating atypical cuboidal cells with hyperchromatic nuclei and nucleoli were distributed in small nests or as single cells and had invaded the stroma. No apparent intercellular bridges or keratinization was observed. Immunohistochemically, the L4 bone marrow tumor cells were diffusely positive for p16 (B). They also produced positive results during HMB-45 (D) and melan-A (F) staining, but negative results during AE1/AE3 (c) and S-100 (e) staining. Similarly, the pharyngeal tumor cells were diffusely positive for p16 (b). They also produced partially positive results during HMB-45 (d), S-100 (e), and melan-A (f) staining and negative results during AE1/AE3 (c) staining.
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As a result, it was diagnosed as a metastatic lesion derived from malignant melanoma because epithelial marker staining produced negative results, and HMB-45 and melan-A staining were positive (Figure 5).