FDG positron emission tomography in patients with systemic mastocytosis

CT and Fluorine-18-Fluorodeoxyglucose (18F-FDG) PET/CT Imaging Findings of Aggressive Systemic Mastocytosis: A Case Report

Aggressive systemic mastocytosis (ASM) is an advanced subtype of systemic mastocytosis characterized by organ involvement. In this article, we report a case with ASM in a 54-year-old woman with characteristic findings on computed tomography (CT) and fluorine-18-fluorodeoxyglucose positron emission tomography (18F-FDG PET)/CT. Contrast-enhanced CT on admission revealed hepatosplenomegaly, generalized osteosclerosis, colonic edema, edematous thickening of the wall in the ascending colon and edema in the surrounding regions of these organs and mesentery, ileus, subcutaneous edema, periportal collar sign, and multiple mesenteric lymphadenopathies. There was no 18F-FDG uptake in the lesions other than mild 18F-FDG uptake in the vertebrae, making the possibility of differential diagnoses such as metastasis, lymphoma, and extramedullary leukemia lower. Based on bone marrow biopsy results and clinical findings, the diagnosis of ASM was established. ASM can be a potentially fatal disease with a poor prognosis, and understanding its distinctive clinical course and imaging findings is crucial for early therapeutic intervention.

Diagnosis and treatment of systemic mastocytosis in Brazil: Recommendations of a multidisciplinary expert panel

INTRODUCTION

Systemic Mastocytosis comprises a group of neoplastic diseases characterized by clonal expansion and infiltration of mast cells into several organs. The diagnosis and treatment of this disease may be challenging for non-specialists.

OBJECTIVE

Make suggestions or recommendations in Systemic Mastocytosis based in a panel of Brazilian specialists.

METHOD AND RESULTS

An online expert panel with 18 multidisciplinary specialists was convened to propose recommendations on the diagnosis and treatment of Systemic Mastocytosis in Brazil. Recommendations were based on discussions of topics and multiple-choice questions and were graded using the Oxford Centre for Evidence-Based Medicine 2011 Levels of Evidence Chart.

CONCLUSION

Twenty-two recommendations or suggestions were proposed based on a literature review and graded according to the findings.

Systemic Mastocytosis Treatment with Midostaurin: [18F]FDG PET/CT as a Potential Monitoring Tool for Therapy Outcome

We report the case of a 68-year-old patient with diagnosed systemic mastocytosis and histopathologically confirmed manifestations in the stomach and intestinal tract who underwent 18F-Fluorodeoxyglucose ([18F]FDG) positron-emission tomography/computed tomography (PET/CT) pre- and post-6-month therapy with midostaurin, an established tyrosine kinase inhibitor. Post-therapeutic [18F]FDG PET/CT showed decreased multifocal tracer uptake in the known lesions in the gastrointestinal tract, which was consistent with relief of the patient’s symptoms and decrease in serum tryptase level. [18F]FDG PET/CT may thus be considered a potential method for monitoring the outcome of midostaurin therapy in systemic mastocytosis.

CXCR4 Expression Demonstrated by 68Ga-Pentixafor PET/CT Imaging in a Case of Systemic Mastocytosis Mimicking Lymphoma

ABSTRACT

68Ga-Pentixafor is a novel radiotracer for imaging chemokine receptor subtype 4 (CXCR4) receptors, which are expressed exceptionally high in several hematologic malignancies, including various types of lymphoma. Herein we report a case of a 64-year-old man patient with suspected hematologic malignancy who underwent 18F-FDG and 68Ga-pentixafor PET/CT. Both scans demonstrated diffusely increased activity related to bone marrow involvement. 68Ga-Pentixafor PET/CT demonstrated CXCR4-expressing intra-abdominal lymph nodes that were not detected by 18F-FDG PET/CT. The patient was highly suspicious of lymphoma; however, histopathological examination of the bone marrow revealed systemic mastocytosis with associated myelofibrosis.

Aggressive systemic mastocytosis with diffuse bone marrow 18F-FDG uptake

Mastocytosis is a clonal hematopoietic disorder characterized by proliferation of abnormal mast cells in various organs including the skin, digestive system, lymph nodes, and bone marrow. We report on a 75-year-old woman presenting with abdominal pain, vomiting, diarrhoea, myalgia, and weight loss. Abdominal CT showed hepatosplenomegaly with heterogeneous splenic parenchyma, lymphadenopathy, and osteopenia with areas of osteosclerosis but no primary tumour. An ¹⁸F-FDG PET/CT revealed an overall low metabolic activity of the lesions with a diffuse bone marrow involvement raising suspicion of a haematological neoplasm. Subsequently, bone marrow and peripheral blood examinations confirmed the diagnosis of aggressive systemic mastocytosis.

Systemic mastocytosis revisited with an emphasis on skeletal manifestations

Systemic mastocytosis (SM) is a rare form of mastocytosis that can affect various organ systems. Bone involvement is the most common and prominent imaging feature in patients with SM regardless of the subtype. Furthermore, bone involvement is a prognostic factor as it may entail an aggressive course of the disease. Diagnosis is established by bone marrow biopsy complemented by imaging modalities such as radiography, CT, and magnetic resonance (MR) imaging. The radiographic and CT appearances are that of sclerotic, lytic, or mixed patterns with focal or diffuse distribution, involving primarily the axial skeleton and the ends of the long bones. Bone marrow infiltration is best recognized on MR imaging. Osteoporosis is common in SM; thus, a bone mineral density measurement at lumbar spine and proximal femur by dual-energy X-ray absorptiometry should be obtained. Imaging plays a huge part in the diagnostic process; when skeletal imaging findings are carefully interpreted and correlated with clinical features, they can lead to the suspicion of SM. The primary aims of this review article were to focus on the role of imaging in detection and characterization of skeletal patterns of SM and to discuss relevant clinical features that could facilitate prompt and correct diagnosis.

Non-hematologic diagnosis of systemic mastocytosis: Collaboration of radiology and pathology

Systemic mastocytosis (SM) is a hematologic disease with a wide range of clinical courses ranging from an indolent condition with normal life expectancy to exceedingly aggressive disorder with a poor prognosis. The symptoms and signs of SM result from the release of mast cell mediators with heterogeneous functions, and/or organ damage from neoplastic mast cell infiltration, or both. Diagnostic criteria for SM are well-defined by the World Health Organization (WHO). However, the diagnosis of SM can be difficult when especially it is not in the differential diagnosis. Routinely used radiologic techniques (e.g., X-ray, ultrasound, CT scans can show findings such as lytic-, sclerotic- or mixed-bone lesions, splenomegaly, hepatomegaly, retroperitoneal or periportal mesenteric lymphadenopathy, and omental thickening). It is essential to emphasize that the constellation of these radiologic findings should strongly concern of SM, especially in patients who also have a skin rash, allergic reactions, gastrointestinal tract symptoms (lasting, intermittent nausea, diarrhea), paroxysmal tachycardias, unexplained weight loss, persistent bone pain, cytopenias, liver dysfunction, eosinophilia. These findings, even coincidentally noted, will likely lead to a tissue biopsy, which reveals diagnosis (as we discussed and illustrated some tissue biopsies here). Moreover, the role of MRI and new techniques such as [18-fluorodeoxyglucose positron emission computed tomography, fibroscan] in the diagnosis of SM have been discussed. Furthermore, we reviewed the use of radiologic methods to evaluate treatment response and prognostication of SM..

Imaging of mast cells

Mast cells are a part of the innate immune system implicated in allergic reactions and the regulation of host-pathogen interactions. The distribution, morphology and biochemical composition of mast cells has been studied in detail in vitro and on tissue sections both at the light microscopic and ultrastructural level. More recently, the development of fluorescent reporter strains and intravital imaging modalities has enabled first glimpses of the real-time behavior of mast cells in situ. In this review, we describe commonly used imaging approaches to study mast cells in cell culture as well as within normal and diseased tissues. We further describe the interrogation of mast cell function via imaging by providing a detailed description of mast cell-nerve plexus interactions in the intestinal tract. Together, visualizing mast cells has expanded our view of these cells in health and disease.

FDG-PET/CT findings in systemic mastocytosis: a French multicentre study

INTRODUCTION

Mastocytosis is a clonal haematological disease characterized by uncontrolled proliferation and the activation of mast cells. The value of FDG-PET/CT (FDG-PET) in mastocytosis has yet to be determined.

METHODS

We retrospectively identified patients with an established diagnosis of systemic mastocytosis (SM), according to the WHO criteria, who underwent PET using the French Reference Centre for Mastocytosis database. Semi-quantitative and visual analysis of FDG-PET was performed and compared to the clinico-biological data.

RESULTS

Our cohort included 19 adult patients, median age 65 years [range 58-74], including three with smouldering SM (SSM), three with aggressive SM (ASM), 10 with an associated clonal haematological non-mast-cell lineage disease (SM-AHNMD), and three with mast cell sarcoma (MCS). FDG-PET was performed at the time of the SM diagnosis (15/19), to evaluate lymph node (LN) activity (3/19) or the efficacy of therapy (1/19). FDG uptake was observed in the bone marrow (BM) (9/19, 47%), LN (6/19, 32%), spleen (12/19, 63%), or liver (1/19, 5%). No significant FDG uptake was observed in the SSM and ASM patients. A pathological FDG uptake was observed in the BM of 6/10 patients with SM-AHNMD, appearing as diffuse and homogeneous, and in the LN of 5/10 patients. All 3 MCS patients showed intense and multifocal BM pathological uptake, mimicking metastasis. No correlation was found between the FDG-PET findings and serum tryptase levels, BM mast cell infiltration percentage, and CD30 and CD2 expression by mast cells.

CONCLUSIONS

FDG uptake does not appear to be a sensitive marker of mast cell activation or proliferation because no significant FDG uptake was observed in most common forms of mastocytosis (notably purely aggressive SM). However, pathological FDG uptake was observed in the SM-AHNMD and in MCS cases, suggesting a role of FDG-PET in their early identification and as a tool of therapeutic assessment in this subgroup of patients.

Systemic mastocytosis: a rare cause of single vertebral body uptake on bone scan

Systemic Mastocytosis is a rare condition characterized by the abnormal proliferation of Mast Cells. Presentation as a solitary vertebral body lesion is extremely uncommon and may be confused with more ominous conditions such as metastasis. Familiarity with the condition can heighten clinical suspicion, direct tissue diagnosis, guide management and indicate appropriate follow up. We present a case of a 64-year-old woman undergoing staging for recently diagnosed breast cancer who was found to have Systemic Mastocytosis of a single vertebral body.

Advanced imaging of skeletal manifestations of systemic mastocytosis

Systemic mastocytosis comprises a group of clonal disorders of the mast cell that most commonly involves the skeletal system. Imaging can be helpful in the detection and characterization of the osseous manifestations of this disease. While radiography and bone scans are frequently used for this assessment, low-dose multidetector computed tomography and magnetic resonance imaging can be more sensitive for the detection of marrow involvement and for the demonstration of the various disease patterns. In this article, we review the pathophysiological and clinical features of systemic mastocytosis, discuss the role of imaging for staging and management, and illustrate the various cross-sectional imaging appearances. Awareness and knowledge of the imaging features of this disorder will increase the accuracy of image interpretation and can contribute important information for management decisions.

Spleen in haematological malignancies: spectrum of imaging findings

Imaging morphology and metabolic activity of splenic lesions is of paramount importance in patients with haematological malignancies; it can alter tumour staging, treatment protocols and overall prognosis. CT, MRI and positron emission tomography (PET)/CT have been shown to be powerful tools for the non-invasive assessment of splenic involvement in various haematological malignancies. Since many haematological malignancies and non-neoplastic conditions can involve the spleen and imaging manifestations can overlap, imaging and clinical findings outside of the spleen should be looked for to narrow the differential diagnosis; confirmation can be obtained by pathological findings. Radiologists should be familiar with the cross-sectional imaging patterns of haematological malignancies involving the spleen as well as non-neoplastic splenic findings common in these patients to facilitate their care and follow-up. This pictorial review provides the common and uncommon imaging appearances and complications of various haematological malignancies involving the spleen on CT, MRI and PET/CT, and common pitfalls in diagnosis.