Increased 18F-FDG Uptake of Widespread Endometriosis Mimicking Ovarian Malignancy

Urinary Endometriosis Misdiagnosed as Ureteral Malignant Tumor by PET/CT: A Case Study

ABSTRACT

Endometriosis is a chronic inflammatory estrogen-dependent benign disease. It is defined as the endometrium growing outside the uterine cavity and the myometrium. It usually has low FDG uptake but rarely occurs in the ureters. We reported a case of a 47-year-old woman's left ureteral nodule originally misdiagnosed as a ureteral malignant tumor by PET/CT and finally pathologically confirmed as endometriosis.

Relaxed fibronectin: a potential novel target for imaging endometriotic lesions

BACKGROUND

Endometriosis is characterized by the ectopic occurrence of endometrial tissue. Though considered benign, endometriotic lesions possess tumor-like properties such as tissue invasion and remodeling of the extracellular matrix. One major clinical hurdle concerning endometriosis is its diagnosis. The diagnostic modalities ultrasound and MRI are often unable to detect all lesions, and a clear correlation between imaging and clinical symptoms is still controversial. Therefore, it was our aim to identify a potential target to image active endometriotic lesions.

RESULTS

For our studies, we employed the preclinical radiotracer [111In]In-FnBPA5, which specifically binds to relaxed fibronectin-an extracellular matrix protein with key functions in homeostasis that has been implicated in the pathogenesis of diseases such as cancer and fibrosis. We employed this tracer in biodistribution as well as SPECT/CT studies in mice and conducted immunohistochemical stainings on mouse uterine tissue as well as on patient-derived endometriosis tissue. In biodistribution and SPECT/CT studies using the radiotracer [111In]In-FnBPA5, we found that radiotracer uptake in the myometrium varies with the estrous cycle of the mouse, leading to higher uptake of [111In]In-FnBPA5 during estrogen-dependent phases, which indicates an increased abundance of relaxed fibronectin when estrogen levels are high. Finally, immunohistochemical analysis of patient samples demonstrated that there is preferential relaxation of fibronectin in the proximity of the endometriotic stroma.

CONCLUSION

Estrous cycle stages characterized by high estrogen levels result in a higher abundance of relaxed fibronectin in the murine myometrium. This finding together with a first proof-of-concept study employing human endometriosis tissues suggests that relaxed fibronectin could be a potential target for the development of a diagnostic radiotracer targeting endometriotic lesions. With [111In]In-FnBPA5, the matching targeting molecule is in preclinical development.

PET/CT imaging in invasive endometriosis: a way to minimize missed diagnosis and reduce invasive interventions

INTRODUCTION

Heterogeneous and nonspecific symptoms make invasive endometriosis a difficult entity to diagnose. Small lesions with absent associated changes can be easily missed in cross-sectional imaging. Even when the lesions satisfy the thresholds for various investigations, their appearance changes with cyclical fluctuations in the hormonal levels. Therefore, newer approaches are needed to achieve correct diagnosis.

METHODS

Six females in reproductive age group (mean age = 32.5 ± 4.3 years) were retrospectively selected, wherein the diagnosis of invasive endometriosis was confirmed after 18F-FDG-PET/CT. Indications for PET/CT were staging in 4 patients, suspected progression in 1 and suspected inflammatory bowel disease in one patient. The study was repeated in proliferative phase in two patients and in the menstrual phase in another patient. FNAC was available in two patients and a drop in CA125 was documented in the last patient.

RESULTS

In five patients metabolically active lesions were seen in PET/CT and in the last, activity was absent despite symptoms. Repeat menstrual phase imaging in the last patient confirmed the diagnosis. In two patients with metabolically active lesions at baseline, resolution was seen in proliferative phase PET/CT. In the other two patients, repeat study was not indicated as FNAC revealed normal endometrial tissue and in the last patient, significant drop in CA125 was documented after just 2 weeks. In all of these patients, the final diagnosis was of invasive endometriosis.

CONCLUSION

In reproductive-age women, PET/CT acquisition should be optimized in the context of menstrual cycle. This approach can be used to non-invasively rule in/rule out endometriosis, especially with repeat imaging in proper menstrual phase.

Interference of Known or Suspected Endometriosis in Reporting FDG PET/CT Performed in Another Indication

INTRODUCTION

Endometriosis is a common gynecologic condition that may be visualized on 18F-FDG PET/CT and mimic lesions of malignancy. We analyzed the interference of known or suspected endometriosis in reporting 18F-FDG PET/CT performed in another indication.

RESULTS

The PET/CT images of 18 women with known (n = 15) or suspected (n = 3) endometriosis were analyzed. Based on clinical follow-up and results of other imaging, biopsy, and/or postsurgical histology, the presence of lesions of endometriosis at the time of 18F-FDG PET/CT was confirmed in 13 of 18 patients (72%). The per-patient positivity rate of 18F-FDG PET/CT was 8/18 (44%; 95% confidence interval, 22%-69%). The patient-based detection rate of 18F-FDG PET/CT in patients with confirmed lesions of endometriosis was 8/13 (62%; confidence interval, 32%-86%). On per-lesion/site basis, 18F-FDG PET/CT detected 11 of 20 sites (55%) of endometriosis. The SUVmax of these lesions/sites ranged between 1.8 and 5.3 (median, 3.8). In 9 of 18 patients (50%), a total of 13 non-endometriosis-related lesions/sites were detected by 18F-FDG PET/CT; their SUVmax ranged between 2.7 and 23 (median, 9.4).

CONCLUSION

The interference of known or suspected endometriosis in reporting 18F-FDG PET/CT performed in another indication was limited but possible and should be kept in mind, even in postmenopausal women, as the oldest patient with 18F-FDG-positive endometriosis was aged 63 years. The lesions of endometriosis showed inconstant 18F-FDG uptake with overlap of SUVmax with low-grade malignancies. In our series, the greatest SUVmax value of lesion of endometriosis was 5.3, somewhat higher than the threshold of 4 previously proposed for identification of malignant transformation of endometriosis.

Pulmonary cavitations with increased 18F-FDG uptake revealing a thoracic endometriosis: A case report

RATIONALE

Thoracic endometriosis is a rare disorder that can involve airways, pleura and lung parenchyma. It is the most frequent form of extra-abdominopelvic endometriosis. Multiple lung cavitations are a rare feature of thoracic endometriosis.

PATIENT CONCERNS

A 46-year-old woman was referred to our hospital after incidental finding of multiple pulmonary cavitations with surrounding areas of ground glass opacity on a thoraco-abdominal computed tomography-scan performed for abdominal pain. Retrospectively, the patient also reported mild hemoptysis occurring 4 months ago.

DIAGNOSES

Positron emission tomography-computed tomography scan revealed moderate and homogeneous [18F] fluoro-2-deoxy-D-glucose (18F-FDG) uptake in pulmonary cavitations (maximum standardized uptake value 5.7). The diagnosis of thoracic endometriosis was confirmed by histological examination of surgical resection of a left lower lobe cavitation.

INTERVENTIONS AND OUTCOME

Gonadotropin-releasing hormone analogues associated with add-back therapy was started. Four months after initiating pharmacological treatment, the chest computed tomography-scan showed a dramatic decrease in lung cavitations size.

LESSONS

Thoracic endometriosis is a rare disorder requiring a multidisciplinary management including gynaecologist, pulmonologist, radiologist, nuclear physician, pathologist and thoracic surgeon for early diagnosis and treatment. Our case report highlights that an increased 18F-FDG uptake can be found in thoracic endometriosis syndrome presenting as multiple lung cavitations.

PET/CT Variants and Pitfalls in Gynecological Cancers

The role of hybrid imaging with 2-[18F] flourodeoxyglucose (FDG) positron emission tomography and computed tomography (PET/CT) is continuously evolving and now considered standard practice in evaluation of disease stage, treatment response, recurrent disease and follow-up for numerous primary malignancies. In gynecological malignancies FDG PET/CT plays an important role, not only in the assessment of disease in the pre-and post-therapy setting, but also in radiation therapy (RT) planning by defining the metabolically active gross tumor volume (GTV. The glucose analogue radiotracer, FDG, is by far the most utilized radiotracer in PET/CT and is typically seen with high uptake in malignant cells. The radiotracer FDG has a high sensitivity but low specificity for malignancy, as benign processes with an inflammatory response for example infection, are also FDG-avid. In the evaluation of the female pelvic region an awareness of potential confounding factors in the interpretation of FDG is essential as variations of FDG uptake occur in accordance with the menstrual cycle and the menopausal state. Incidental imaging findings in the female genital can pose differential diagnostic challenges as false-positive and false-negative findings in benign and malignant processes are not uncommon. Gynecological malignancies continue to pose major public health problems with cervical cancer as the fourth most common cancer in women ranking after breast cancer, colorectal cancer and lung cancer. Familiarity with frequently encountered benign and malignant variants and pitfalls in FDG PET/CT in the female pelvic region can aid the reader in differential diagnostic considerations.

A case report of bladder and intestinal endometriosis, and the relationship between sex hormone receptor expression and PIK3CA mutation analysis

BACKGROUND

Extragonadal endometriosis is a rare condition, and its disease manifestation and long-term prognosis have not been elucidated. We report an extragonadal endometriosis case controlled by drug therapy for 14 years with analysis of the sex hormone receptor expression and PIK3CA mutation.

CASE PRESENTATION

The patient was diagnosed with bladder endometriosis at age of 30 years, and underwent bilateral nephrostomy and GnRHa therapy with add-back therapy. The patient was switched to dienogest therapy at age 35 and had hematuria and bloody stools at age 38. PET-CT revealed a 6-cm mass in the bladder with fluorodeoxyglucose accumulation and the diagnosis of endometriosis in the bladder, sigmoid colon, and cecum was confirmed after the biopsy result. The lesion's tubular structures were positive for the estrogen receptor, but only 30% positive for the progesterone receptor, and the H1047R mutation in PIK3CA was found in tubular structures of the bladder lesion. GnRHa therapy caused the tumors to shrink.

CONCLUSION

Decreased progesterone receptor expression and oncogenic mutations may influence the course of less common and rare site endometriosis. Rare site endometriosis often requires long-term hormone therapy, and management should be tailored to the patient's life stage, keeping in mind complications, such as decreased bone density.

Polypoid endometriosis: a mimic of malignancy

This an interesting case of an asymptomatic 60-year-old postmenopausal patient with an incidental pelvic mass mimicking a pelvic malignancy on imaging. Biopsy revealed findings consistent with polypoid endometriosis. After discontinuation of hormone replacement therapy, the mass showed decrease in size on follow-up imaging. Polypoid endometriosis is a rare but distinct variant of endometriosis with histopathologic features akin to an endometrial polyp. Clinical and imaging features of polypoid endometriosis differ from classic endometriosis. While classic endometriosis predominates in premenopausal women, polypoid endometriosis more commonly affects peri- to postmenopausal women and is associated with the exposure to Tamoxifen or hormone replacement therapy. Imaging features that aid in the diagnosis of polypoid endometriosis are a T2 hyperintense polypoid mass with signal characteristics similar to endometrium, a T2 hypointense peripheral rim, contrast enhancement pattern mirroring the enhancement of the endometrium, and lack of diffusion restriction. Radiologists should be familiar with polypoid endometriosis because this clinically and morphologically distinct variant may mimic malignant neoplasms on imaging.

New biomarkers in endometriosis

Endometriosis is a benign gynecological disorder which presents significant challenges in terms of diagnosis and management. Despite decades of research, there are no sufficiently sensitive and specific signs and symptoms nor blood tests for the clinical confirmation of endometriosis, which hampers prompt diagnosis and treatment. The huge majority of potential biomarkers has been discarded in research stage and very few have been translated to clinical practice. Serum CA-125 is the most studied and used one, but studies have shown its poor diagnostic performance. Several factors involved in the chronic inflammatory process of endometriosis, such as hormones, cytokines, chemokines, angiogenic factors, oxidative stress markers and others, have been implicated in the disease's pathogenesis and have been extensively studied, but not a single one has successfully been able to accurately identify the disease. MicroRNAs have emerged more recently but their utility to detect endometriosis remains uncertain. The search for a biomarker or a set of biomarkers is still open and may benefit from novel molecular biology and bioinformatics approaches to mine and uncover molecular signatures specifically associated with the disease.

Endometriosis resembling endometrial cancer in a postmenopausal patient

Endometriosis occurs in 2-4% of postmenopausal women. There have been a few reports of endometriosis in women in whom neither history nor diagnostic imaging indicated the presence of this disease, either at reproductive age or after menopause. A case is described of an 84-year-old patient with extensive deep pelvic endometriosis imitating advanced neoplastic process.

Endometriosis Mimicking an Advanced Malignant Tumor

A 27-year-old woman with swelling left leg, groin pain, and increased serum CA125 level underwent FDG PET/CT to evaluate a pelvic mass revealed by an MRI performed from an outside hospital. A large hypermetabolic solid mass in the left pelvic wall and several lymph nodes with elevated FDG activity were noted, which indicated malignancy. However, histopathological examination demonstrated endometriosis.

Unusual Case of Postmenopausal Diffuse Endometriosis Mimicking Metastastic Ovarian Malignancy

Endometriosis is a common gynecologic condition of the premenopausal years. However, postmenopausal endometriosis is rare (2.2%) and thought to be related to high level of circulating estrogen, especially in hormonal replacement therapy. We present a case of a 69-year-old postmenopausal woman, previously healthy and on no regular medication, with diffuse peritoneal endometriosis and bilateral ovarian endometrioma mimicking metastatic ovarian carcinoma on FDG PET/CT. Both ovarian endometrioma had low-grade activity, but more strikingly, there was diffuse FDG-avid peritoneal dissemination and gross ascites. Endometriosis should not be totally disregarded as a differential diagnosis even at postmenopausal status.

Ovarian Hyperstimulation and Oocyte Harvesting Prior to Systemic Chemotherapy-A Possible Pitfall in 18F-FDG PET/CT Staging of Oncologic Patients

A 33-year-old woman with Hodgkin disease Ann Arbor stage IIA underwent baseline F-FDG PET/CT scanning. The scan showed gross multicystic enlargement of both ovaries and a nodule at the edge of the right ovary with intense FDG uptake (SUVmax = 14.8). Differential diagnosis would include ovarian lymphoma manifestation, endometrioma, and ovarian or pelvic neoplasia. However, chart analysis revealed previous superstimulation with gonadotropins and gonadotropin release hormone antagonist, and transvaginal oocyte retrieval the day before FDG PET/CT. This led to the diagnosis of ovarian hyperstimulation syndrome, with the FDG-avid focus representing a hemorrhagic follicle after transvaginal oocyte retrieval procedure.

Serum folate receptor alpha as a biomarker for ovarian cancer: Implications for diagnosis, prognosis and predicting its local tumor expression

Folate receptor alpha (FRA) is a GPI-anchored glycoprotein and encoded by the FOLR1 gene. High expression of FRA is observed in specific malignant tumors of epithelial origin, including ovarian cancer, but exhibits very limited normal tissue expression, making it as an attractive target for the ovarian cancer therapy. FRA is known to shed from the cell surface into the circulation which allows for its measurement in the serum of patients. Recently, methods to detect the soluble form of FRA have been developed and serum FRA (sFRA) is considered a highly promising biomarker for ovarian cancer. We prospectively investigated the levels of sFRA in patients clinically suspected of having malignant ovarian tumors. A total of 231 patients were enrolled in this study and analyzed for sFRA as well as tumor expression of FRA by immunohistochemistry. High sFRA was predominantly observed in epithelial ovarian cancer patients, but not in patients with benign or borderline gynecological disease or metastatic ovarian tumors from advanced colorectal cancers. Levels of sFRA were highly correlated to clinical stage, tumor grade and histological type and demonstrated superior accuracy for the detection of ovarian cancer than did serum CA125. High sFRA was significantly associated with shorter progression-free survival in both early and advanced ovarian cancer patients. Finally, tumor FRA expression status was strongly correlated with sFRA levels. Taken together, these data suggest that sFRA might be a useful noninvasive serum biomarkers for future clinical trials assessing FRA-targeted therapy.