Rationale: Pembrolizumab, a monoclonal antibody against the programmed cell death 1 (PD-1) protein, can induce a stable regression of some malignancies refractory to conventional chemotherapy. Despite such therapeutic benefits, pembrolizumab can induce immune-related adverse events, with pneumonitis being the most critical problem. Patient concerns: All 3 patients complained of fever, cough, and dyspnea after a variable time interval (1–21 days) from pembrolizumab treatment. Diagnoses: Chest computed tomography invariably showed ground glass opacity. All tests for possible infectious agents were negative. Based on high procalcitonin level, one of 3 patients was diagnosed to have accompanying bacterial pneumonia. Interventions: All patients received antibiotics and steroid treatments (methylprednisolone, 1 mg/kg). Outcomes: The 3 patients showed different clinical courses ranging from mild pneumonitis to rapidly progressing respiratory failure. Among the 3 patients, 2 fully recovered with steroid treatment; 1 died from superimposed bacterial pneumonia. Lessons: The prognosis of pembrolizumab-induced pneumonitis with a superimposed bacterial pneumonia would be poor. It is important to distinguish pure pneumonitis from that with a superimposed bacterial pneumonia.

Metastasis to the thyroid gland is uncommon, with previous autopsy series showing incidence rates ranging from 0.5% to 10.1% [1][2][3][4][5][6][7]. Clinical reports have suggested, however, that the incidence of these metastases is increasing. The most common primary carcinoma sites in clinical reports are the kidneys, breasts, and lungs [8][9][10][11][12][13][14], although other primary carcinomas can also metastasize to the thyroid gland [15][16][17][18][19][20][21][22][23][24][25][26][27].Hepatocellular carcinoma (HCC) rarely metastasizes to the thyroid [6,23,[25][26][27]. Here, we describe a patient with an HCC metastasis to within a medullary thyroid carcinoma (MTC), that is, a tumor-in-tumor metastasis. To our knowledge, this is the first such clinically diagnosed case.Due to the relatively short survival times of patients with distant metastases, solitary thyroid tumors in patients with advanced carcinoma are not routinely evaluated. However, imaging modalities, including fluorine-18 fluorodeoxyglucose positron emission tomography (FDG-PET) and ultrasonography (US) guided fine-needle aspiration biopsy (FNAB) of newly detected Hepatocellular carcinoma eats medullary thyroid carcinoma, a case of tumor-in-tumor metastasis abstract. Carcinoma metastasis to the thyroid is uncommon, but may be increasing. We describe here a patient with a metastasis of hepatocellular carcinoma (HCC) presenting within a medullary thyroid carcinoma (MTC). The thyroid tumor was detected synchronously with the hepatic lesion by FDG-PET imaging, and HCC metastasis within MTC was confirmed by histological analysis of the thyroid gland.

We present a case of mandibular involvement with Langerhans cell histiocytosis (LCH), diagnosed by ultrasound-guided aspiration and subsequently confirmed by incisional biopsy and immunohistochemistry in an eight-year-old boy. The cytologic findings included the presence of characteristic Langerhans cells of both mononucleate and multinucleate form. Diagnostic confirmation was obtained by immunopositivity for S-100 protein and CD1a of Langerhans histiocytes on paraffin-embedded sections obtained during incisional biopsy of the right mandibular area. By reporting a case of childhood LCH, we correlate the cytologic findings with histologic features and discuss the role of aspiration cytologic diagnosis in such a rare and cytomorphologically characteristic case.