Cytomorphology of gastrointestinal stromal tumors and extra-gastrointestinal stromal tumors: A comprehensive morphologic study

Metastatic gastrointestinal stromal tumour in pleural fluid 19 years after initial diagnosis

Gastrointestinal stromal tumours (GISTs) are rarely encountered in pleural fluid samples. We report a case of GIST metastatic to pleural fluid almost two decades after the original diagnosis. Careful screening by a cytotechnologist, consideration of the clinical history, and judicious use of immunohistochemical stains facilitated the uncommon diagnosis.

Spindle cell lesions of the abdomen: Not always GIST!

The cytological differential diagnoses of gastrointestinal stromal tumours are mesenchymal, neural and neuroendocrine tumours. However, there are potential pitfalls, two of which are presented here.

Interstitial Cells of Cajal-Origin, Distribution and Relationship with Gastrointestinal Tumors

The interstitial cells of Cajal (ICC) represent a particular network formed by some peculiar cells that were first described by the great neuroanatomist, S. Ramon y Cajal. Nowadays, the ICC have become a fascinating topic for scientists, arousing their curiosity; as a result, there is a vast number of published articles related to the ICC. Today, everybody widely accepts that the ICC represent the pacemaker of the gastrointestinal tract and are highly probable to be the origin cells for gastrointestinal tumors (GISTs). Recently, Cajal-like cells (ICLC) were described, which are found in different organs but with an as yet unknown physiological role that needs further study. New information regarding intestinal development indicates that the ICC (fibroblast-like and muscle-like) and intestinal muscle cells have the same common embryonic cells, thereby presenting the same cellular ultrastructure. Nowadays, there is a vast quantity of information that proves the connection of the ICC and GISTs. Both of them are known to present c-kit expression and the same ultrastructural cell features, which includes minimal myoid differentiation that is noticed in GISTs, therefore, supporting the hypothesis that GISTs are ICC-related tumors. In this review, we have tried to highlight the origin and distribution of Cajal interstitial cells based on their ultrastructural features as well as their relationship with gastrointestinal stromal tumors.

Incidental diagnosis of a spindle cell type gastrointestinal stromal tumor in a dog with ethylene glycol intoxication

A 6-year-old castrated male American Pit Bull Terrier dog was presented for evaluation of acute onset of tonic-clonic seizures, anorexia, and vomiting. On physical examination, neurologic signs, such as generalized proprioceptive ataxia, salivation, circling to the right, and absent patellar reflexes bilaterally, were noted. A complete blood cell count revealed mild hemoconcentration and an inflammatory leukogram, while a chemistry panel showed severe azotemia, marked hypochloremia, and a severe titrational metabolic acidosis, suggesting possible ethylene glycol intoxication. However, an irregularly round, small mass was identified in the large intestine on abdominal ultrasound. Additionally, bilateral hyperechoic renal cortices with medullary rim sign were suggestive of acute nephritis or tubular necrosis. The cytologic evaluation of a fine-needle aspiration biopsy of the abdominal mass revealed a large population of mesenchymal cells, suggesting the presence of neoplasia. Due to the worsening of symptoms, the dog was humanely euthanized. Necropsy confirmed ethylene glycol intoxication, and the incidental finding of a neoplastic intestinal mass was diagnosed as spindle cell sarcoma. Immunohistochemical staining showed strong, diffuse positivity for CD117, smooth muscle actin, and S-100, indicating the final diagnosis of a spindle cell type gastrointestinal stromal tumor (GIST). This report briefly discusses the classifications of nonlymphoid, nonangiogenic intestinal mesenchymal tumors, characteristics of GISTs, and the importance of the immunohistochemical classification of mesenchymal tumors of the gastrointestinal tract.

Spindle cell neoplasms of the upper gastrointestinal tract, hepatobiliary tract, and pancreas by fine needle aspiration: A single institutional experience of 15 years with follow-up data

BACKGROUND

The diagnosis of spindle cell neoplasms (SCN) of the upper gastrointestinal (GI) tract, hepatobiliary tract, and pancreas detected by fine needle aspiration (FNA) is challenging. We describe a single-center experience of these samples with follow-up data and characterization of the morphologic findings.

METHODS

We retrospectively reviewed pathology records for all FNAs diagnostic for or suggestive of SCN on esophagus, stomach, small bowel, liver, and pancreas in a 15 year period. All cases with at least 6 month follow-up were included. Surgical material (biopsy or resection) was the diagnostic gold standard. All FNAs with subsequent surgical specimens were reviewed and assessed for cellularity, architectural features, and nuclear features.

RESULTS

In 15 years, 5101 FNAs of the upper GI tract, hepatobiliary tract, and pancreas were performed. SCN was diagnosed in 98 (2%) patients. Seventy-two patients had definitive pathologic diagnoses: 68 were neoplastic and four were non-neoplastic. Cytomorphologic review in relationship to final diagnosis revealed three statistically significant features: low cellularity favors a benign process (P = .00544), epithelioid nuclear morphology favors malignancy (P = .00278), and identification of perinuclear vacuoles favors a diagnosis of GIST over non-GIST SCN (P = .04236).

CONCLUSIONS

Among cases with follow-up, final pathologic diagnoses were SCN in 94% of cases diagnosed as SCN on FNA of upper GI, hepatobiliary tract, and pancreas. Although some cytomorphologic criteria are more suggestive of malignancy, arriving at a specific diagnosis relies on collaboration of clinical, radiologic, cytomorphologic, and immunohistochemical data.

Succinate dehydrogenase-deficient gastrointestinal stromal tumor of stomach diagnosed by endoscopic ultrasound-guided fine-needle biopsy: Report of a distinct subtype in cytology

Succinate dehydrogenase (SDH)-deficient gastrointestinal stromal tumors (GISTs) are characterized by the lack of mutations in KIT receptor tyrosine kinase complex and platelet derived growth factor receptor-alpha (PDGFRA) that are commonly found in the majority of GISTs. SDH-deficient GISTs comprise approximately 5%-10% of all GISTs. This subset may be associated with Carney Triad and Carney-Stratakis syndrome. SDH-deficient GISTs show unique demographic, radiologic, morphologic findings, clinical behavior, and treatment response. To our knowledge, the identification and characterization of this subset of GISTs have not yet been described in the cytopathology literature. By understanding the clinical as well as the other unique features of this tumor, in addition to the rapidly evolving identification of specific molecular alterations and targeted therapies, cytopathologists may play an important role in the diagnosis and work-up of these patients to allow clinicians to better manage and treat them. We present a young female with gastric SDH-deficient GIST diagnosed by fine-needle biopsy with supporting surgical pathology follow-up and molecular confirmation. This report suggests that the diagnosis of SDH-deficient GIST can be made on cytology in the appropriate clinical setting by using cytomorphologic features and demonstrating SDH loss by IHC on the cell block. In addition, molecular testing may be possible on the cytology cell block or supernatant to confirm the diagnosis.

Mesenchymal neoplasms of the tubular gut and adjacent structures: experience with EUS-guided fine-needle aspiration cytopathology

INTRODUCTION

Unlike epithelial malignancies, mesenchymal neoplasms arising within the tubular gut are less often encountered in endoscopic ultrasound-guided (EUS) fine-needle aspiration biopsies (FNABs). Nonetheless, preoperative diagnosis of such neoplasms has important therapeutic and prognostic value. We report our experience with this category of neoplasms from the past decade.

MATERIALS AND METHODS

We performed a 10-year retrospective search at our respective institutions to identify EUS-guided FNAB cases of mesenchymal neoplasms arising from the tubular gut wall and closely adjacent structures. Cytopathologic diagnoses were compared to corresponding surgical pathology (SP) when available. Cases with either no confirmatory cell block (CB) immunohistochemical (IHC) staining, or no SP were excluded.

RESULTS

Two-hundred eighty-two cases (M:F = 1:1; age range: 25-94 years, mean age = 60 years) of EUS-guided FNAB from the tubular gut met our criteria. Onsite adequacy was performed on nearly all cases. Case numbers: 209 gastrointestinal stromal tumors (GIST), 58 smooth muscle neoplasms, and 15 miscellaneous neoplasms. Of these, 188 (67%) had SP follow-up. We found that 258 (91%) aspirates had a correct specific diagnosis, 3 (1%) were nondiagnostic, 18 (6%) had indeterminate diagnoses, and 3 (1%) had incorrect diagnoses (2 leiomyosarcomas mistaken as leiomyoma, and 1 fibrosclerotic lesion mistaken as inflammatory pseudotumor). Of 94 cases with no SP, all had a specific cytologic diagnosis based on confirmatory IHC staining from the CB including 61 GISTs, 29 smooth muscle neoplasms, and 4 miscellaneous tumors.

CONCLUSION

This study endorses the clinical utility of EUS-guided FNAB in the diagnosis of tubular gut mesenchymal neoplasms. A definitive and accurate diagnosis is possible in over 90% of cases, chiefly when cytomorphology is coupled with optimal cellularity and IHC from a concurrent CB. EUS-guided FNAB diagnosis of mesenchymal tubular gut neoplasms may play an important role in determining neoadjuvant therapy as targeted therapy evolves.

A Huge Pelvic-Abdominal Malignant GIST Tumour in a Patient with Neurofibromatosis Type 1: Case Report and Literature Review

Gastrointestinal stromal tumours are rare tumours of the gastrointestinal tract (GIT) accounting for 0.1%–3% of all gastrointestinal tumours. The most common location is the stomach (55%) followed by the small bowel (31.8%), colon (6%), other various locations (5.5%), and the oesophagus (0.7%). They may also occur in extraintestinal locations. The signs and symptoms of GIST depend on the tumour's location and size. Gastrointestinal bleeding is one of the most common symptoms. Other signs and symptoms include abdominal discomfort, pain or distention; intestinal obstruction, and weight loss. The association between the development of GISTs and neurofibromatosis 1 (NF1) has been established. NF1-associated GISTs tend to have a distinct phenotype, and the absence of KIT/PDGRFα mutations in turn has implications on further management when they do not respond well to imatinib treatment. Here, we present one of the largest GISTs reported in the literature with a total volume of 25.3 × 20 × 14 cm + 27.9 × 23 × 8 cm and an overall weight of 7.3 kg, which developed in a 43-year-old female patient with NF1 and was resected on an emergency basis due to the rapid deterioration and development of abdominal compartment syndrome. Pathology assessment showed a malignant GIST composed of spindle cells with elongated nuclei with necrosis, marked pleomorphism and numerous giant cell. The mitotic count was >15/50 HPF, Ki 67 was 80%, and the lymphovascular invasion was clear. Immunohistochemistry investigations showed that Vimentin, CD117, and DOG1 were positive, while BCL-2 and CD99 were focal positives. Pan-CK, S-100, CD34, Desmin, SMA, and HMB-45 were negatives.

Analysis of clinicopathological and immunohistochemical parameters and correlation of outcomes in gastrointestinal stromal tumors

INTRODUCTION

Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal tumors of the gastrointestinal tract. We analyzed the clinicopathological features, resectability, immunohistochemical markers, and various factors predictive of disease recurrence and survival.

MATERIALS AND METHODS

Retrospective analysis of prospectively maintained database of GIST patients managed from 2005 to 2016 was done. Size, site, malignant potential, nuclear pleomorphism, histopathological variety, immunohistochemical markers, type of surgery, and adjuvant imatinib therapy were analyzed.

RESULTS

Ninety-two patients with GIST were analyzed. Immunohistochemistry showed positivity for c-kit (82.4%), DOG1 (75%), and PDGFR-α (79%). Among 16 patients with c-kit-negative tumors, 10 patients were positive for DOG1, PDGFR-α, or both. The most common primary site was stomach (44, 47.8%) followed by small bowel (17, 18.5%) and duodenum (14, 15.2%). Of 92 patients, 80 (87%) underwent R0 resection with organ sparing resection in 56 (70%) patients. Seventeen (21.3%) patients showed recurrence at a median follow-up of 6 years. Median and 5-year overall survival (OS) was 36 months (12-120) and 75%, respectively, and 5-year RFS was 81.8%. On univariate analysis, size, mitotic activity, malignant potential, and nuclear pleomorphism were predictors of recurrence. However, on multivariate analysis, only nuclear pleomorphism was significant.

CONCLUSIONS

GISTs had a wide spectrum of presentation, and immunohistopathological features with organ sparing resection were conceivable in maximum. Nuclear pleomorphism may be considered as an important variable to predict recurrence in addition to malignant potential of tumors.

Role of Novel Marker Discovered on Gastrointestinal Stromal Tumor 1 in Evaluation of Gastrointestinal Stromal Tumors

Background: Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal tumors arising from myenteric ganglion cells, termed interstitial cells of Cajal. GISTs occur predominantly between 40 and 60 years of age. CD34 was the initially used for diagnosing GIST. Due to its low specificity for GISTs, CD34 was replaced by C-KIT, which is a reliable marker. However, 5% GISTs lack C-KIT expression. Recent studies have shown GIST1 (DOG1) to be a more sensitive and specific marker compared to C-KIT and CD34. Aims and Objectives: The aim was to study histomorphology characteristics and risk stratification of all cases previously diagnosed as GISTs, to evaluate these cases for CD117 and DOG1 expression by immunohistochemistry (IHC) and to see whether there was any advantage in using novel markers (i.e. DOG1) as compared to conventional (C-KIT) in GIST at our center. Materials and Methods: Fifty patients with histomorphologic or imaging impression of GIST were subjected to IHC using C-KIT and DOG1. Results and Conclusion: Of 50 cases 47 (94%) were positive for C-KIT, and all 50 (100%) cases were positive for DOG1. Hence, DOG1 was positive even in C-KIT-negative cases. Therefore, our study suggests that DOG1 should be added to workup of suspected cases of GIST along with C-KIT.

Rectal gastrointestinal stromal tumor with metastasis to the penis: Case report and review of literature

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The first reported case of a rectal GIST with metastasis to the penis is documented by this report.

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The primary cancer was treated with neoadjuvant chemotherapy and abdominoperineal resection.

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Biopsies of lesions identified on follow-up imaging were consistent with metastatic GIST.

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Metastasectomy and adjuvant chemotherapy have been utilized to help prolong survival.

We report the case of a 51-year-old gentleman with previously diagnosed gastrointestinal stromal tumor (GIST) of the rectum with metastasis to the penis. The patient underwent abdominoperineal resection of the primary tumor with negative margins and completed a three-year course of imatinib mesylate (Gleevec). Forty months after resection of his rectal tumor, the patient presented to his urologist with worsening testicular pain, mild lower urinary tract obstructive symptoms, and nocturia. A pelvic MRI revealed the presence of an ill-defined mass in the right perineum extending from the base of the penis to the penoscrotal junction. Biopsy of this mass was consistent with metastatic GIST. To our knowledge, this is the first report of metastatic GIST to the penis.

A rare case of giant gastrointestinal stromal tumor of the stomach involving the serosal surface

INTRODUCTION

Although rare, gastrointestinal stromal tumors (GIST) are the most common mesenchymal tumors affecting the gastrointestinal tract.

PRESENTATION OF CASE

Here we report the case of a 43-year-old man complaining of abdominal pain along with a painless and palpable mass, which was confirmed on magnetic resonance and multislice computed tomography. Laparotomy revealed a nodular grayish-white firm noninfiltrative mass (39×27×14cm, 6109g) that was well localized within the extramuscular and peritoneal surface of the anterior wall of the stomach; complete tumor resection was performed. Histopathological examination revealed features typical of GIST, including increased cellularity, increased mitotic activity, and spindle shaped cells as well as positive immunoreactivity for KIT, CD34, and vimentin.

DISCUSSION

A review of literature revealed that GISTs of the size and weight similar to the present case has been rarely reported. GIST most frequently involves the stomach. Although the etiopathogenesis of this disease remains unclear, few well-documented familial cases have been associated with GIST syndromes.

CONCLUSION

The primary treatment preferred is complete surgical excision of the tumor.

Utility of DOG1 Immunomarker in Fine Needle Aspirates of Gastrointestinal Stromal Tumor

BACKGROUND

Gastrointestinal stromal tumor (GIST) is the most common mesenchymal tumor of the gastrointestinal tract. DOG1 is a sensitive and specific immunohistochemical marker for the diagnosis of GIST. To date, no study has reported the utility of DOG1 immunocytochemistry on aspirate smears.

METHODS

Aspirates with a cytological diagnosis of GIST were retrieved. DOG1 immunocytochemistry was performed on aspirates with adequate material.

RESULTS

23 cases were included (11 primary, 2 recurrent, 10 metastatic). Primary tumors were most frequently located in the stomach; most metastatic tumors were in the liver. Tumor cells were arranged in cohesive clusters with high cellularity. Cells were spindled, had a low N:C ratio, and a moderate amount of cytoplasm, which was elongated and tapering. Characteristic nuclear features included elongated nuclei with blunt or tapering ends, fine chromatin, mild anisonucleosis, and longitudinal grooves. The mitotic count was low, including in metastatic tumors. DOG1 immunopositivity was noted in 57% of the cases examined. Histopathology was available in 5 cases, all diagnosed as GIST.

CONCLUSION

Cytology is a sensitive investigative modality for the preoperative diagnosis and confirmation of metastasis of GISTs. In ambiguous cases, DOG1 immunocytochemistry can serve as a valuable adjunct. Cytologic assessment, however, cannot predict malignant potential of GISTs as even metastatic tumors display bland nuclear features.