Background Anaplastic lymphoma kinase (ALK)-positive histiocytosis, a novel rare histiocytic proliferation, was first described in 2008; it occurs in early infancy with liver and hematopoietic involvement. The spectrum was subsequently broadened to include localized diseases in older children and young adults. However, its full clinicopathological features and molecular lineage have not been fully elucidated. Results Here, we report four cases of multisystem ALK-positive histiocytosis without hematopoietic involvement. Clinically, three patients were adults aged between 32 and 51 years. Two patients’, whose main manifestations were intracranial mass and numerous micronodules in the thoracoabdominal cavity organs and skin papules respectively, had a partial response to ALK inhibitors after surgery. One patient presented with mediastinal neoplasm without surgical treatment, and progressive disease occurred after two years of ALK inhibitor therapy. The fourth patient was a 17-month-old male with a large intracranial mass and presented with a poor response to ALK inhibitor and chemoradiotherapy; he died eight months after surgery. Pathologically, the histiocytes were large, with abundant eosinophilic cytoplasm, and mixed with variable numbers of foamy cells and Touton giant cells. Interstitial fibrosis was also observed. Histiocytes were positive for macrophage markers (CD68 and CD163) and ALK. KIF5B-ALK fusions were detected in two cases, EML4-ALK in one, and both DCTN1-ALK and VRK2-ALK fusions were detected in one case. Conclusions We observed that ALK inhibitors present robust and durable responses in adult patients but a poor response in young children with central nervous system involvement. There is no consensus on the optimal treatment regimen and long-term prognosis requires further observation. Moreover, every unusual histiocytic proliferative lesion, especially unresectable and multisystem involvement, should be routinely tested for ALK immunohistochemical staining to identify this rare disease.

Background Congenital peribronchial myofibroblastic tumor (CPMT) is an extremely rare lung disease in infants. It shows benign behavior and has a favorable survival after surgical treatment. CPMT was reported only in cases. Here, we report the longest follow-up known case of CPMT and review the clinical, radiographic and histopathological features of the published literature. Case presentation Ultrasound examination at 30 weeks of gestational age of a healthy 29-year-old female revealed a solid mass in the left lung. Computed tomography (CT) revealed a mass in the left lower lobe. The tumor was removed by lobectomy and pathologically diagnosed with CPMT. The tumor was composed of cartilage, spindle cells and oval cells. Vimentin was strongly positive. Smooth muscle actin (SMA) was positive in the spindle cells. The histopathologic and immunohistochemical features were similar to those in the literature. No ETV6-NTRK3 fusion or ALK rearrangement was detected. Gene mutations in JAK2 and SMO were detected by NGS. She is currently alive for 8 years with no evidence of disease recurrence. Conclusions CPMT is a rare lung tumor in infants. Surgical treatment is recommended for CPMT. The prognosis after successful surgery is favorable. The final diagnosis was histopathologic findings. Due to its cellularity, mitotic activity and rapid growth, long-term follow-up should be strengthened. The present patient is alive and well for 8 years after the surgery without recurrence. Gene mutations in JAK2 and SMO were detected, which may be associated with the formation of CPMT.

EGFR mutations other than 19Del and L858R are called uncommon mutations and account for ~10% of all EGFR mutations. 1,2 These mutations have almost identified 600 variants, and represent a highly heterogeneous group with distinct clinical features. 3,4 Being excluded from most prospective clinical trials, the evidence for EGFR uncommon mutations have been mainly derived from retrospective studies or combined post-hoc analysis of trials with limited sample size due to the rarity of this setting. [5][6][7] Only two small-scale studies have prospectively evaluated the efficacy of EGFR-TKIs for uncommon mutations. Osimertinib demonstrated activity with an ORR of

BackgroundPersistent pulmonary interstitial emphysema (PPIE) is known to be related to mechanical ventilation and preterm. However, PPIE is also reported rarely in non-ventilated and full-term infants. Its relationship with respiratory infection is rarely reported in the literature. PPIE is difficult to diagnose and always mimics other congenital thoracic malformations (CTMs), such as congenital cystic adenomatoid malformation (CCAM).ObjectiveThe objective of this study was to evaluate clinicopathological and radiographic features of PPIE with respiratory infection and to detect the possible infectious pathogens.MethodsFrom January 2011 to December 2019, six cases were confirmed pathologically with PPIE from a large cohort of 477 resected CTMs in West China Hospital of Sichuan University. Clinical and radiographic features were obtained from patients' medical records and follow-up. The present study aimed to analyze clinicopathological and radiographic features and to detect the infectious pathogens by metagenomic next-generation sequencing (mNGS).ResultsThe six PPIE cases included four girls and two boys, ranging from 2 months to 5 years; 100% (5/5) of the available cases were full-term and without mechanical ventilation. CCAM were suspected in 66.7% (4/6) patients; 66.7% (4/6) cases affected a single lobe, and 33.3% (2/6) cases affected both lung lobes. Clinically, all six PPIEs were presented with symptoms of respiratory infection and diagnosed with pneumonia. All six patients were treated by surgery after anti-infective treatment. The pathologic characteristics showed lung cysts with variable size along the bronchovascular bundles, the cysts had a discontinuous fibrotic wall with a smooth inner surface lined with uninucleated and/or multinucleated macrophages. Streptococcus pneumoniae was detected in patient No. 1. Human beta-herpesvirus 5 was detected in patient No. 2. Neisseria mucosa, Neisseria sicca, Prevotella melaninogenica, Prevotella histicola, and Fusobacterium nucleatum were detected in patient No. 5, and no infectious pathogen was detected in 50% (3/6, No. 3, No. 4, and No. 6) of cases.ConclusionSix rare cases of PPIE with respiratory infection were treated by surgery after anti-infective treatment. All five available cases were full-term infants without mechanical ventilation. The histological characteristics of PPIE were the wall of cysts composed of a thin layer of discontinuous fibrous tissue and lined with uninucleated or/and multinucleated macrophages.