A 79-year old woman was hospitalized on April 25, 2018, at which time she had progressive dyspnea over the past 5 weeks, productive cough, poor appetite, and weight loss of 5 kg over the last 6 months currently weighing 81 kg. Her medical history included an invasive ductal breast cancer pT1cN0M0 G2 ER 90%, PR 20% 20 years ago treated with lumpectomy, radiotherapy, and tamoxifen until 2004, and an undifferentiated cancer of the right parotid pT1 (17 mm) pN2 (1/2 positive in level I, 1/11 positive in level II, no extranodal extensions) pM0 diagnosed 2008 and treated with a total parotidectomy achieving R0 margins and a selective neck dissection levels II-IV followed by radiotherapy.\nOn physical examination, the patient was in mild respiratory distress. The pulmonary exam revealed dullness to percussion, decreased fremitus, and decreased breathing sounds in up to two-thirds of the left lung field. Oxygen saturation was 92% with the patient breathing ambient air, and arterial blood gases showed partial respiratory insufficiency. A chest X-ray confirmed a left-sided pleural effusion, and thoracentesis removed 1.5 liters of turbid fluid. Biochemical analysis of the fluid established an exudative etiology. Atypical cells with immunocytochemical positivity for p40, cytokeratin 5, and p63 in the cytopathology specimen were primarily suggestive of a non-small cell lung cancer, and a CT scan of the thorax showed a mass (4.2 × 2.2 × 2.8 cm) in the right upper lobe and extensive cardiophrenic, mediastinal, and hilar lymphadenopathy as well as enlarged lymph nodes along the left arteria mammaria interna. An FDG PET/CT scan confirmed these findings, and the scan revealed a hypermetabolic activity in mesenteric lymph nodes and at the left pleura (). Thoracoscopy and biopsy of the parietal pleura were performed. Surprisingly, histopathological examination revealed a non-small cell carcinoma () expressing CD5 (), CD117 (), and p63 all indicating a carcinoma of thymic origin (). With no signs of a thymic pathology, the histopathological diagnosis of CASTLE was established, and as additional immunostainings for CD5 () and CD117 () in the specimen of the parotid cancer diagnosed 2008 were positive also, a rare case of a CASTLE tumor of the parotid healed at the primary and neck sites, but with late metastatic dissemination was diagnosed.\nAs CD117 was highly overexpressed in the tumor, exons 9, 11, 13, 14, and 17 of the C-KIT gene were analyzed after extraction of genomic DNA by PCR using specific primers, but no common mutation was found consistent with previous reports (, ). Anticancer immunity and potential response to immunotherapy were assessed by PD-L1 staining of the pleural tumor, which showed a high expression level of 60% ().\nThe patient underwent talc pleurodesis and left partial pleurectomy for recurrent pleural effusions. Systemically, disseminated metastatic disease was treated with the monoclonal PD-L1 inhibitor pembrolizumab at a dose 200 mg every 3 weeks. Four months after the start of immunotherapy a follow-up FDG PET/CT study showed a partial remission with a moderate morphologic reduction of the tumor load, but a markedly reduced metabolic activity at all tumor sites (). Pembrolizumab treatment continued at a dose of 200 mg IV every 3 weeks. The patient showed a mild skin rash treated with low dose prednisolone (20 mg with tapering) for 2 weeks. No other adverse events associated with pembrolizumab were observed, and the therapy was tolerated well. At the last follow-up, the patient was in good clinical condition and had gained 3 kg of weight. On March 28th, 2019, a second follow-up FDG PET/CT showed no residual pleural effusion (not shown) and a further regression of lesions in the right lung and lymph nodes. Residual focal FDG-Uptake was seen in the left pleura ().
A 76-year-old man was referred to our hospital for investigation of a 20-day history of rapidly deteriorating dyspnea and severe cough. This was associated with dysphagia and cervical pain. The patient was an ex-marble craftsman and an active smoker. His medical history included chronic pulmonary obstructive disease (COPD). A chest X-ray (CXR) showed an imprint at the right side of the trachea. Thyroid ultrasound (US) revealed a large and heterogenous thyroid gland and the presence of a calcified mass, 4.76 × 4.01 cm with high blood perfusion in the right upper lobe of the gland. A contrast-enhanced computed tomography (CT) scan of the neck and thorax reported the corresponding lesion as heterogenous, with irregular borders, extending from the sternoclavicular joints to the upper borders of the thyroid gland. The mass was surrounding the trachea anterolaterally displacing it to the left and the right common artery to the right (). There were no enlarged lymph nodes. Bronchoscopy revealed a fracture of the first tracheal ring but there was no evidence of tumour invasion (). Cytology from bronchial lavage was negative for cancer cells. Laboratory tests were within normal limits with the exception of elevated D-dimers (2,994 μg/L) and elevated white blood cells (19.27 K/μL). Tumour markers were within normal range values.\nOn admission, the patient was intubated, due to acute respiratory failure, and he was admitted to the intensive care unit (ICU). Subsequently, he underwent an emergency procedure and a collar incision was carried out. At surgery, a suspicious looking tumour, which was in continuity with the superior pole of the right thyroid lobe, the sheath of right common carotid artery, and the anterolateral portion of the cartilaginous trachea, was identified. Macroscopically, the tumour looked whitish and scleroelastic with moderately regular borders and was firmly adhered to the aforementioned structures. After the right recurrent laryngeal nerve was identified, the tumour was carefully dissected off the right thyroid lobe and the adventitia of the right common carotid artery. A similar approach was carried out to dissect the tumour off the left lobe; hence, an en bloc tumour resection with total thyroidectomy and a regional lymph node dissection was performed. Rapid frozen section biopsy of the tumour in the right thyroid lobe proved to be malignant with features of squamous cell carcinoma and negative surgical margins.\nPostoperatively, the patient experienced swallowing difficulty and hoarseness and a tracheostomy was performed on day 2.\nFinal pathology examination confirmed frozen section's diagnosis of a squamous cell carcinoma invading the right lobe of the thyroid gland, as well as extracapsular structures of the left lobe. Microscopically, the tumour was described as nonencapsulated, irregularly lobulated, with broad fibrous septa, and lymphoplasmacytic, eosinophilic, histiocytic, and multinuclear infiltration. The neoplastic cells were largely polyhedral or oval with eosinophilic or amphophilic cytoplasm, arranged in islands or nests that showed focal keratinization. The nuclei were vesicular or hyperchromatic with nucleoli. A panel of immunohistochemical stains was performed; the tumour was positive for p63, CD117, CKH, CD5, and CD3 in the lymphocytic part (Figures , , and ). It was also negative for the expression of TTF1.\nThe patient subsequently improved and was discharged home on postoperative day 20. The patient did not receive any additional treatment.