• Extragastrointestinal stromal tumor
• GIST
• Gastrointestinal stromal tumor
• Stromal tumor

Primary hepatic stromal tumours are very rare and there are only sporadic reports in the literature. Due to the lack of specificity in their clinical manifestations and imaging features, these tumours are easily misdiagnosed. This current report presents a case of primary liver stromal tumour that was misdiagnosed as a liver cyst. The 72-year-old male patient was admitted to the hospital due to right upper abdomen fullness and discomfort for more than 2 weeks. Colour Doppler ultrasonography and enhanced computed tomography examinations revealed a cystic mass in the right lobe of the liver. The preoperative diagnosis was a liver cyst and the laparoscopic fenestration was performed. The pathological examination demonstrated that it was a primary hepatic stromal tumour. Gastroenteroscopy was performed postoperatively and no lesions were found in the gastrointestinal tract. Imatinib mesylate was given orally as the salvage therapy and a radical operation was planned at the patient's request. This current case serves as a reminder that clinicians should consider the possibility that it could be a primary hepatic stromal tumour rather than a hepatic cyst. A multidisciplinary team is necessary for the diagnosis and treatment of patients with a primary hepatic stromal tumour.

Gastrointestinal stromal tumors (GIST), which is the most common mesenchymal tumor of the digestive tract, account for 1%-3% of gastrointestinal tumors. Primary stromal tumors outside the gastrointestinal tract are collectively referred to as extra GISTs, and stromal tumors in different regions often have different prognoses. A primary hepatic GIST is a rare tumor with an unknown origin, which may be related to interstitial Cajal-like cells. Although primary hepatic GIST has certain characteristics on imaging, it lacks specific symptoms and signs; thus, the final diagnosis depends on pathological and genetic evidence. This review summarizes all cases of primary hepatic GIST described in the literature and comprehensively analyzes the detailed clinical data of all patients. In terms of treatment, local resection alone or with adjuvant therapy was the prioritized choice to obtain better disease-free survival and longer survival time. For advanced unresectable cases, imatinib mesylate was applied as the first-line chemotherapy agent. Moreover, transcatheter arterial chemoembolization, radiofrequency ablation, and microwave ablation were shown to improve overall survival for selected patients. Liver transplantation was a final treatment option after resistance to chemotherapy developed.

• Extra gastrointestinal stromal tumor
• Treatment
• Liver transplant
• Review

• Antineoplastic Agents/therapeutic use
• Benzamides/therapeutic use
• Carcinoma, Hepatocellular
• Chemoembolization, Therapeutic
• Gastrointestinal Neoplasms/diagnosis
• Gastrointestinal Neoplasms/epidemiology
• Gastrointestinal Neoplasms/therapy
• Gastrointestinal Stromal Tumors/diagnosis
• Gastrointestinal Stromal Tumors/epidemiology
• Gastrointestinal Stromal Tumors/therapy
• Humans
• Liver Neoplasms/epidemiology
• Liver Neoplasms/therapy
• Piperazines/therapeutic use
• Prevalence
• Pyrimidines

• cellular communication
• exosomes
• pancreas
• soft-shelled turtle
• telocytes
• telopodes

• endothelial cell
• interstitial cell
• lymphatic
• telocytes

• EGIST
• Gall bladder
• Gallstones
• Liver
• Telocytes

• Feature
• gastrointestinal stromal tumor
• liver
• prognosis

A 67-year-old female presented with a primary hepatic gastrointestinal stromal tumor that was detected by computed tomography and diagnosed based on histopathological and genetic analyses. The tumor was microscopically composed of spindle cells and epithelioid cells, and immunohistochemistry results showed positive staining for CD117 and CD34 expression. A genetic analysis revealed a heterozygous point mutation and deletion in exon 11 of c-KIT. After an R0 resection, imatinib mesylate was administered for 1 year until its use was discontinued due to severe side effects. Two years after the original operation, the tumor recurred in the residual liver and was completely resected again. Imatinib mesylate was administered for 2 years until it was replaced by sunitinib malate because of disease progression. The patient has survived for 53 mo after undergoing a sequential therapy consisting of surgical excision, imatinib and sunitinib.

• Gastrointestinal stromal tumor
• Diagnosis and treatment
• Tyrosine kinase inhibitor
• Sequential therapy
• Liver

• Aged
• Antineoplastic Agents/administration & dosage
• Antineoplastic Agents/adverse effects
• Benzamides/administration & dosage
• Benzamides/adverse effects
• Biomarkers, Tumor/analysis
• Biomarkers, Tumor/genetics
• Biopsy
• Chemotherapy, Adjuvant
• DNA Mutational Analysis
• Drug Substitution
• Female
• Gastrointestinal Stromal Tumors/chemistry
• Gastrointestinal Stromal Tumors/genetics
• Gastrointestinal Stromal Tumors/pathology
• Gastrointestinal Stromal Tumors/therapy
• Hepatectomy
• Humans
• Imatinib Mesylate
• Immunohistochemistry
• Indoles/administration & dosage
• Liver Neoplasms/chemistry
• Liver Neoplasms/genetics
• Liver Neoplasms/pathology
• Liver Neoplasms/therapy
• Mutation
• Piperazines/administration & dosage
• Piperazines/adverse effects
• Protein Kinase Inhibitors/administration & dosage
• Protein Kinase Inhibitors/adverse effects
• Pyrimidines/administration & dosage
• Pyrimidines/adverse effects
• Pyrroles/administration & dosage
• Sunitinib
• Time Factors
• Tomography, X-Ray Computed
• Treatment Outcome

• Aorta-gonad-mesonephros
• CD117
• CD45
• Endothelial tip cells
• Interstitial cells of Cajal
• c-Kit

• Actins/metabolism
• Adult
• Dendritic Cells/physiology
• Embryonic Stem Cells/physiology
• Female
• Fetus/cytology
• Fetus/physiology
• Gastrointestinal Tract/cytology
• Gastrointestinal Tract/embryology
• Gastrointestinal Tract/physiology
• Hematopoietic Stem Cells/physiology
• Humans
• Interstitial Cells of Cajal/physiology
• Leukocyte Common Antigens/metabolism
• Myenteric Plexus/cytology
• Myenteric Plexus/embryology
• Neovascularization, Physiologic/physiology
• Pregnancy
• Proto-Oncogene Proteins c-kit/genetics
• Proto-Oncogene Proteins c-kit/metabolism

• Angiogenesis
• Circulating fibrocytes
• Fibroblasts
• Iris
• Progenitor cells
• Stem cells

Telocytes (Tcs) are cells with telopodes (Tps), which are very long cellular extensions with alternating thin segments (podomers) and dilated bead-like thick regions known as podoms. Tcs are a distinct category of interstitial cells and have been identified in many mammalian organs including heart, lung and kidney. The present study investigates the existence, ultrastructure, distribution and contacts of Tcs with surrounding cells in the uterus (shell gland) of the oviduct of the Chinese soft-shelled turtle, Pelodiscus sinensis. Samples from the uterine segment of the oviduct were examined by transmission electron microscopy. Tcs were mainly located in the lamina propria beneath the simple columnar epithelium of the uterus and were situated close to nerve endings, capillaries, collagen fibres and secretory glands. The complete morphology of Tcs and Tps was clearly observed and our data confirmed the existence of Tcs in the uterus of the Chinese soft-shelled turtle Pelodiscus sinensis. Our results suggest these cells contribute to the function of the secretory glands and contraction of the uterus.

• Chinese soft-shelled turtle (Pelodiscus sinensis)
• telocytes
• ultrastructure
• uterus

Telocytes (TCs) have been described in various organs and species (www.telocytes.com) as cells with telopodes (Tps) – very long cellular extensions with an alternation of thin segments (podomers) and dilated portions (podoms). We examined TCs using electron microscopy (EM), immunohistochemistry (IHC), immunofluorescence (IF), time-lapse videomicroscopy and whole-cell patch voltage clamp. EM showed a three-dimensional network of dichotomous-branching Tps, a labyrinthine system with homocellular and heterocellular junctions. Tps release extracellular vesicles (mean diameter of 160.6±6.9 nm in non-pregnant myometrium and 171.6±4.6 nm in pregnant myometrium), sending macromolecular signals to neighbouring cells. Comparative measurements (non-pregnant and pregnant myometrium) of podomer thickness revealed values of 81.94±1.77 vs 75.53±1.81 nm, while the podoms' diameters were 268.6±8.27 vs 316.38±17.56 nm. IHC as well as IF revealed double c-kit and CD34 positive results. Time-lapse videomicroscopy of cell culture showed dynamic interactions between Tps and myocytes. In non-pregnant myometrium, patch-clamp recordings of TCs revealed a hyperpolarisation-activated chloride inward current with calcium dependence and the absence of L-type calcium channels. TCs seem to have no excitable properties similar to the surrounding smooth muscle cells (SMCs). In conclusion, this study shows the presence of TCs as a distinct cell type in human non-pregnant and pregnant myometrium and describes morphometric differences between the two physiological states. In addition, we provide a preliminary in vitro electrophysiological evaluation of the non-pregnant state, suggesting that TCs could influence timing of the contractile activity of SMCs.

Recently, a novel type of stromal cell – the telocytes (TC) – was identified in mouse trachea. These cells are known to possess the ultrastructural characteristics, which support their role in intercellular signaling. We found TC in all stromal compartments of the tracheal wall. TC with long prolongations (telopodes, Tp) were lining longitudinally the collagen bundles, and were serially arranged (end-to-end connections of Tp were found). Noteworthy, Tp frequently establish stromal synapses with mast cells (MC). Primary cilia were also identified in TC. In conclusion, tracheal TC could be involved in the tracheal regulation (e.g. secretion, contractility). The tandem TC-MC deserves further investigations.

We used rat experimental myocardial infarction to study the ultrastructural recovery, especially neo-angiogenesis in the infarction border zone. We were interested in the possible role(s) of telocytes (TCs), a novel type of interstitial cell very recently discovered in myocardim (see http://www.telocytes.com). Electron microscopy, immunocytochemistry and analysis of several proangiogenic microRNAs provided evidence for TC involvement in neo-angiogenesis after myocardial infarction. Electron microscopy showed the close spatial association of TCs with neoangiogenetic elements. Higher resolution images provided the following information: (a) the intercellular space between the abluminal face of endothelium and its surrounding TCs is frequently less than 50 nm; (b) TCs establish multiple direct nanocontacts with endothelial cells, where the extracellular space seems obliterated; such nanocontacts have a length of 0.4–1.5 μm; (c) the absence of basal membrane on the abluminal face of endothelial cell. Besides the physical contacts (either nanoscopic or microscopic) TCs presumably contribute to neo-angiognesis via paracrine secretion (as shown by immunocytochemistry for VEGF or NOS2). Last but not least, TCs contain measurable quantities of angiogenic microRNAs (e.g. let-7e, 10a, 21, 27b, 100, 126-3p, 130a, 143, 155, 503). Taken together, the direct (physical) contact of TCs with endothelial tubes, as well as the indirect (chemical) positive influence within the ‘angiogenic zones’, suggests an important participation of TCs in neo-angiogenesis during the late stage of myocardial infarction.

We advance the hypothesis that the telocyte might be the cell of origin of both PEComas (perivascular epithelioid cell tumours) and GISTs (gastro-intestinal and extra-gastrointestinal stromal tumours). The hypothesis is supported by data from the literature reporting that both PEComas and GISTs, as well as telocytes, share the expression of several markers. These data were supplemented by original immunohistochemical tests on selected series. Specifically: (1) Melanoma markers (Melan A, MiTF) typical of PEComas are expressed by a substantial fraction of GISTs. A fraction of GISTs was also found positive for CD63, a tetraspanin protein originally described in melanomas and marking exosomes. (2) c-KIT (CD117), proper of the vast majority of GISTs, can be expressed by PEComas (as well as by telocytes). (3) Markers described in telocytes (CD34, S-100, smooth muscle actin and vascular endothelial growth factor) have been reported as positive in cases of PEComas and GISTs. Telocytes show distinctive ultrastructural features with thin, extended, telopodes and are likely involved in inter-cellular signalling via paracrine secretion as well as by shed vesicles and exosomes. These cells have been described in many locations (cavitary and non-cavitary organs) and might display potentialities of a wide spectrum of differentiation (and function). In conclusion we propose that telocytes could be the common cells of origin for both PEComas and GISTs.

This study describes a novel type of interstitial (stromal) cell — telocytes (TCs) — in the human and mouse respiratory tree (terminal and respiratory bronchioles, as well as alveolar ducts). TCs have recently been described in pleura, epicardium, myocardium, endocardium, intestine, uterus, pancreas, mammary gland, etc. (see www.telocytes.com). TCs are cells with specific prolongations called telopodes (Tp), frequently two to three per cell. Tp are very long prolongations (tens up to hundreds of μm) built of alternating thin segments known as podomers (≤ 200 nm, below the resolving power of light microscope) and dilated segments called podoms, which accommodate mitochondria, rough endoplasmic reticulum and caveolae. Tp ramify dichotomously, making a 3-dimensional network with complex homo- and heterocellular junctions. Confocal microscopy reveals that TCs are c-kit- and CD34-positive. Tp release shed vesicles or exosomes, sending macromolecular signals to neighboring cells and eventually modifying their transcriptional activity. At bronchoalveolar junctions, TCs have been observed in close association with putative stem cells (SCs) in the subepithelial stroma. SCs are recognized by their ultrastructure and Sca-1 positivity. Tp surround SCs, forming complex TC-SC niches (TC-SCNs). Electron tomography allows the identification of bridging nanostructures, which connect Tp with SCs. In conclusion, this study shows the presence of TCs in lungs and identifies a TC-SC tandem in subepithelial niches of the bronchiolar tree. In TC-SCNs, the synergy of TCs and SCs may be based on nanocontacts and shed vesicles.