Endometrioma Presenting as a Cavitary Lung Mass With Intense 18F-FDG Uptake on PET-CT

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.

Intense FDG Uptake in Leiomyomatosis Peritonealis Disseminata With Fumarate Hydratase Deficiency

ABSTRACT

A 35-year-old woman with a history of laparoscopic myomectomy presented with repeated abdominal pain. Contrast-enhanced abdominal and pelvic CT showed multiple enhancing solid or mixed cystic and solid peritoneal masses, and an enhancing uterine mass. All these masses showed intense FDG uptake on FDG PET/CT. The intraperitoneal and uterine masses were surgically removed. The histological and immunohistochemical findings of the peritoneal lesions were consistent with leiomyomatosis peritonealis disseminata with fumarate hydratase deficiency, and the uterine mass was adenomyosis. This case indicates fumarate hydratase-deficient extrauterine leiomyoma can show intense FDG uptake mimicking malignancy.

18 F-FDG PET/CT to Spare Malignancy in a Rare Case of Lung Endometriosis

ABSTRACT

Lung endometriosis is a rare condition. A 44-year-old woman with known lung endometriosis and radiological follow-up showed progression of bilateral lung affection at control CT, with an enlarged solid nodule with respect to previous control. 18 F-FDG PET/CT was performed to assess that lesion and to guide biopsy. PET images showed the multiple known nodules with pathological tracer uptake.

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.

Retroperitoneal Endometriosis: A Possible Cause of False Positive Finding at (18)F-Fluorodeoxyglucose Positron Emission Tomography/Computed Tomography

Endometriosis is a frequent and clinically relevant problem in young women. Laparoscopy is still the gold standard for the diagnosis of endometriosis, but frequently both morphologic and functional imaging techniques are involved in the diagnostic course before achieving a conclusive diagnosis. We present a case of a patient affected by infiltrating retroperitoneal endometriosis falsely interpreted as a malignant mass by contrast-enhanced magnetic resonance imaging and (18)F-fluorodeoxyglucose positron emission tomography/computed tomography.

18F-Fluorodeoxyglucose Positron Emission Tomography/Computed Tomography-Positive Lymph Node Endometriosis Masquerading as Lymph Node Metastasis of a Malignant Tumor

Endometriosis is defined as the presence of endometrium-like tissues at extrauterine sites, most commonly in the abdominal cavity. Lymph node endometriosis is a rare but clinically important type of endometriosis that can mimic lymph node metastasis of a malignant tumor.18F-fluorodeoxyglucose (18F-FDG) positron emission tomography/computed tomography (PET/CT) is a useful tool for diagnosing malignant tumors, although it occasionally shows false positive results in tissues with high metabolic activity caused by severe inflammation. In the present report, we describe a case of lymph node endometriosis that mimicked lymph node metastasis of a malignant tumor and showed a positive result on18F-FDG PET/CT. The findings of the present case suggest that lymph node endometriosis could present as swollen lymph nodes with18F-FDG PET/CT-positive results and provide important information for determining an appropriate treatment strategy.

The antibody-mediated targeted delivery of interleukin-10 inhibits endometriosis in a syngeneic mouse model

BACKGROUND

Endometriosis is still a highly underdiagnosed disease, and the current medical and surgical treatment of endometriosis is associated with a high recurrence rate. This study investigates the use of derivatives of the human antibody F8, specific to the alternatively spliced extra-domain A of fibronectin (Fn), for the imaging and treatment of endometriosis.

METHODS

Immunohistochemistry and immunofluorescence was used to evaluate antigen expression in endometriotic tissue of human endometriosis and of a syngeneic mouse model of the disease. The in vivo targeting performance of a fluorescent derivative of the F8 antibody was assessed by imaging mice with endometriosis using a near-infrared fluorescence imager, 24 h following i.v. injection of the antibody conjugate. Furthermore, the mouse model was used for therapy experiments using two recombinant F8-based immunocytokines [F8-interleukin-10 (IL10) and F8-IL2] or saline for the treatment groups.

RESULTS

A very strong vascular expression of splice isoforms of Fn and of tenascin-C was observed in human endometriotic lesions by immunohistochemistry and immunofluorescence techniques. After i.v. administration, a selective accumulation of the F8 antibody in endometriotic lesions could be observed in a syngeneic mouse model. These targeting data were used as a basis for therapy experiments with a pro-inflammatory (F8-IL2) and an anti-inflammatory (F8-IL10) cytokine fusion protein of the F8 antibody. The average lesion size in the F8-IL10 treatment group was clearly reduced compared with the saline control group and with the F8-IL2 group, for which no therapeutic effects were observed.

CONCLUSIONS

The F8 antibody targets endometriotic lesions in vivo in a mouse model of endometriosis and may be used for the non-invasive imaging of the disease and for the pharmacodelivery of anti-inflammatory cytokines, such as IL10.

Large-muscle endometriosis involving the adductor tight compartment: case report

Extrapelvic endometriosis is an uncommon condition but can involve nearly every organ, resulting in a wide range of clinical manifestations. Herein, we describe the case of a 45-year-old woman not a candidate for hormonal therapy who had cyclic pain in the left thigh associated with progressive impairment of walking ability. Clinical, instrumental, and laboratory data supported the diagnosis of endometriosis involving the adductor muscles compartment associated with ovarian endometriomas. Laparoscopic bilateral salpingo-oophorectomy and local wide excision in collaboration with an experienced orthopedic oncologist were performed, and definitive histologic analysis confirmed the diagnosis of endometriosis. The patient was pain-free at 6-month follow-up and demonstrated substantial improvement in ambulation and quality of life. Large-muscle endometriosis is a rare entity that can compromise musculoskeletal integrity and decrease quality of life. In this case, surgical excision in collaboration with an orthopedic oncologist was the cornerstone of treatment.