FDG PET/CT in carcinoma of unknown primary

Squamous cell carcinoma of unknown primary site presenting with an abdominal wall lesion as the primary symptom: A case report and review of the literature

Squamous cell carcinoma of unknown primary site (SC CUP) is a rare malignant tumor, and its histogenesis and appropriate treatment are unclear. To the best of our knowledge, this type of carcinoma with abdominal wall lesions as the primary presenting symptom 3 months after laparoscopic surgery, has not been previously described in the literature. In the present study, a postmenopausal 54-year-old female patient was diagnosed with pain from the right abdominal puncture site 3 months after laparoscopic unilateral left salpingo-oophorectomy at a local hospital, at which time the left ovary and Fallopian tube were free of malignant tumor. Computed tomography (CT) imaging showed a subcutaneous nodule with a size of 6.2×3.3 cm. A wide excision of the lesion with safety margins and repair of the abdominal wall was performed, and the histopathological results and various investigations lead to the diagnosis of metastatic well-differentiated SC CUP. The patient underwent three surgeries and eight cycles of Taxol and cisplatin/carboplatin chemotherapy, and received a total of 10.8 Gy palliative radiation. However, the patient succumbed to intestinal bleeding, thrombocytopenia and multiple organ failure with pelvic recurrence and liver metastases at 10 months post-diagnosis. The prognosis of SC CUP, particularly with multiple metastases, is extremely poor. Although chemotherapy, surgery and radiotherapy have a certain role in the treatment, no regimen has been established as a standard therapy and palliative care could be recommended.

Diagnosis of Dual Malignancy by 18F-FDG PET/CT in the Setting of Paraneoplastic Cerebellar Degeneration

We describe a rare case of paraneoplastic cerebellar degeneration (with detectable antineuronal antibody anti-Yo) in which (18)F-FDG PET/CT aided in the detection of 2 synchronous malignancies (one thyroid cancer and the other breast cancer). Interestingly, the primary breast malignancy was non-(18)F-FDG-avid and was detected through the presence of a metastatic (18)F-FDG-avid axillary lymph node. Surgery for both was undertaken in the same sitting, and there was improvement of the neurologic features soon after the surgical removal of the malignancies.

Contrast-enhanced [18F] fluorodeoxyglucose-positron emission tomography-computed tomography as an initial imaging modality in patients presenting with metastatic malignancy of undefined primary origin

Background:

To evaluate the advantages of contrast enhanced F-18-fluorodeoxyglucose (FDG) positron emission tomography-computed tomography (PET-contrast enhanced CT [CECT]) when used as an initial imaging modality in patients presenting with metastatic malignancy of undefined primary origin (MUO).

Materials and Methods:

A total of 243 patients with fine needle aspiration cytology/biopsy proven MUO were included in this prospective study. Patients who were thoroughly evaluated for primary or primary tumor was detected by any other investigation were excluded from the analysis. Totally, 163 patients with pathological diagnosis of malignancy but no apparent sites of the primary tumor were finally selected for analysis. The site of probable primary malignancy suggested by PET-CECT was confirmed by biopsy/follow-up.

Results:

PET-CECT suggested probable site of primary in 128/163 (78.52%) patients. In 30/35 remaining patients, primary tumor was not detected even after extensive work-up. In 5 patients, where PET-CECT was negative, primary was found on further extensive investigations or follow-up. The sensitivity, specificity, positive predictive value and negative predictive value of the study were 95.76%, 66.67%, 88.28% and 85.71% respectively.

Conclusions:

F-18 FDG PET-CECT aptly serves the purpose of initial imaging modality owing to high sensitivity, negative and positive predictive value. PET-CECT not only surveys the whole body for the primary malignancy but also stages the disease accurately. Use of contrast improves the diagnostic utility of modality as well as help in staging of the primary tumor. Although benefits of using PET-CECT as initial diagnostic modality are obvious from this study, there is a need for a larger study comparing conventional methods for diagnosing primary in patients with MUO versus PET-CECT.

Is 2-deoxy-2-[(18)F]fluoro-D-glucose PET/CT acquisition from the upper thigh to the vertex of skull useful in oncological patients?

AIM

To assess whether performing routinely 2-deoxy-2-[(18)F]fluoro-D-glucose PET/CT ((18)FDG PET/CT) scan from the upper thigh to the vertex of skull is clinically relevant.

MATERIALS AND METHODS

3502 (1634 female; mean-age 60+16) consecutive patients undergoing (18)FDG PET/CT were retrospectively analyzed. Patients were divided in 10 groups according to primary malignancy. Chi-square analysis was used to assess differences among proportions. A p value < 0.05 was considered significant.

RESULTS

(18)FDG PET/CT was positive in head district in 130/3502 (3,7%) patients. In all patients lesions were unknown before PET/CT examination. PET/CT showed 158 positive brain/head uptake in the 130 patients. The 158 lesions were localized in: brain (43/158; 27%), bone (52/158; 33%), lymph node (1/158; 0,6%), soft tissue (55/158; 35%) and other sites (7/158; 4,4%). According to each group, patients were positive in the head district in 1.0% for Gastrointestinal Cancer (7/690), 3.0 % for Genitourinary Cancer (3/101), 3.7 % for Haemathologic Cancer (59/1590), 2.7 % for Gynaecologic Cancer (3/112), 7.8% for Head-Neck-Thyroid and Parathyroid Cancer (26/331), 3.5% for Breast Cancer (7/200), 2.6% for Lung Cancer (7/271), 3.4% for Melanoma (2/59), 7.4% for Sarcoma (2/27), 11.6% for Unknown Primary Tumour (14/121).

CONCLUSION

Our data show a relatively high incidence of brain/head lesion in patients with Unknown Primary Tumour.

(18)F-FDG PET/CT in Patients with Nodular Pulmonary Amyloidosis: Case Report and Literature Review

A 62-year-old woman was found to have multiple bilateral pulmonary nodules showing different ¹⁸F-fluorodeoxyglucose (FDG) uptakes on positron-emission tomography/computed tomography (PET/CT). Only the largest nodule in the left lower lobe showed an increased ¹⁸F-FDG uptake on PET/CT. Three nodules were surgically resected from different lobes of the left lung. Two lobes were benign and showed amyloid deposition. The largest nodule in the left lower lobe showed adenocarcinoma and a heavy amyloid deposition. Pulmonary amyloidosis should be added to the differential diagnosis for cases with multiple pulmonary nodules that show different ¹⁸F-FDG uptakes on PET/CT. To the best of our knowledge, this is the second reported case of a lung nodule consisting of adenocarcinoma and amyloid deposition.

Detection of occult primary tumors in patients with cervical metastases of unknown primary tumors: comparison of (18)F FDG PET/CT with contrast-enhanced CT or CT/MR imaging-prospective study

PURPOSE

To assess diagnostic accuracy of fluorine 18 ((18)F) fluorodeoxyglucose (FDG) combined positron emission tomography (PET) and computed tomography (CT) in the detection of occult primary tumors and determination of optimal care in patients with cervical metastasis of an unknown primary tumor (CUP) compared with contrast material-enhanced CT alone or combined contrast-enhanced CT and magnetic resonance (MR) imaging (CT/MR imaging).

MATERIALS AND METHODS

Institutional review board approval and written informed consent were obtained. In total, 56 patients with initially undetected tumors after endoscopic or physical examination were prospectively assessed with (18)F FDG PET/CT and contrast-enhanced CT or contrast-enhanced CT/MR imaging. The contrast-enhanced CT/MR images were read in combination. Results of guided biopsy with general anesthesia served as the reference standard. Diagnostic values of (18)F FDG PET/CT, contrast-enhanced CT, and contrast-enhanced CT/MR imaging were compared with the McNemar test.

RESULTS

Primary tumors were detected at 32 sites in 31 (55%) of 56 patients. There were 26 tumors in the palatine tonsil, two in the hypopharynx, two in the base of the tongue, and two in the nasopharynx. PET/CT depicted 22 (69%) of 32 primary tumors, but it failed to depict primary tumors in 10 (31%) of 32 cases. Overall, sensitivity of PET/CT (69%) in detection of primary tumors was higher than that of contrast-enhanced CT (16%) (P < .001) or contrast-enhanced CT/MR imaging (41%) (P = .039), while specificity of these methods did not differ (88%, 76%, and 59% for PET/CT, contrast-enhanced CT, and contrast-enhanced CT/MR imaging, respectively; P > .4). Diagnostic performance (area under the receiver operating characteristics curve [AUC] = 0.759) of PET/CT in tumor detection was significantly better than that of contrast-enhanced CT alone (AUC = 0.531) (P = .001) or contrast-enhanced CT/MR imaging (AUC = 0.537) (P = .036). PET/CT depicted primary tumors in eight (50%) of 16 cases of false-negative CT/MR imaging findings, one distant metastatic case, and two cases of synchronous cancer.

CONCLUSION

(18)F FDG PET/CT is more sensitive in detection of primary tumors than is contrast-enhanced CT or contrast-enhanced CT/MR imaging in patients with CUP; therefore, it may lead to improved therapeutic planning in these patients.

[Importance of nuclear medicine diagnostics in CUP syndrome]

CLINICAL/METHODICAL ISSUE

The diagnostic work-up in patients with carcinoma of unknown primary (CUP) syndrome is extensive, highly time-consuming and cost-intensive and ultimately often fails to detect a primary site.

STANDARD RADIOLOGICAL METHODS

In this context chest X-ray and computed tomography (CT) have been used as standard imaging modalities in CUP syndrome.

METHODOLOGICAL INNOVATIONS

Since the introduction of positron emission tomography (PET) evaluation of tumor vitality has become possible. Furthermore, PET-CT hybrid scanners allow the combination of functional and morphological imaging.

PERFORMANCE

Several meta-analyses have reported an additional overall detection rate between 24.5 % and 44 % by either PET or PET-CT. Metastatic localization (cervical versus extracervical) did not influence the performance. The sensitivity was usually high (> 80 %) but specificity was moderate ranging from 68 % to 88 % at best. If mentioned, the results obtained by fluorodeoxyglucose (FDG)-PET significantly changed the clinical management in approximately one third of the patients studied. In a direct comparison with PET alone, PET-CT did not depict significantly more primary tumors but was able to reduce false positive findings.

ACHIEVEMENTS

To determine the real additional value of PET-CT in the diagnosis of CUP syndrome large prospective studies with more uniform inclusion criteria are needed. Despite the capabilities of FDG-PET-CT there is as yet no evidence that a potentially improved diagnostic algorithm is translated into a better patient outcome.

PRACTICAL RECOMMENDATIONS

Nevertheless, FDG-PET-CT should be performed in all CUP patients where conventional imaging failed to detect a primary site or the results are equivocal. In CUP patients with cervical lymph node metastases PET-CT should be carried out prior to panendoscopy to reduce the number of false negative biopsies.

Potential role of FDG PET/CT in evaluating patients with hepatic incidentalomas

This review article is focused on the role of FDG PET/CT in diagnosing and characterizing hepatic incidentalomas. A large variety of unsuspected lesions can be detected in the liver both with ultrasound and CT performed for other reasons; the prevalence of liver incidentalomas increases in patients with chronic liver disease or preexisting oncologic history. The major challenge is to discriminate benign from malignant lesions. There is a large body of literature indicating that FDG PET/CT is a useful tool to this purpose even if it is unspecific (ie, it cannot differentiate a primary tumor from a secondary lesion). Occasionally, FDG PET/CT can be useful for biopsy guidance.

A case of metastatic cancer with markedly elevated PSA level that was not detected by repeat prostate biopsy

Background

Prostate-specific antigen (PSA) is a widely used specific tumor marker for prostate cancer. We experienced a case of metastatic prostate cancer that was difficult to detect by repeat prostate biopsy despite a markedly elevated serum PSA level.

Case presentation

A 64-year-old man was referred to our hospital with lumbar back pain and an elevated serum PSA level of 2036 ng/mL. Computed tomography, bone scintigraphy, and magnetic resonance imaging showed systemic lymph node and osteoblastic bone metastases. Digital rectal examination revealed a small, soft prostate without nodules. Ten-core transrectal prostate biopsy yielded negative results. Androgen deprivation therapy (ADT) was started because of the patient’s severe symptoms. Twelve-core repeat transrectal prostate biopsy performed 2 months later, and transurethral resection biopsy performed 5 months later, both yielded negative results. The patient refused further cancer screening because ADT effectively relieved his symptoms. His PSA level initially decreased to 4.8 ng/mL, but he developed castration-resistant prostate cancer 7 months after starting ADT. He died 21 months after the initial prostate biopsy from disseminated intravascular coagulation.

Conclusion

CUP remains a considerable challenge in clinical oncology. Biopsies of metastatic lesions and multimodal approaches were helpful in this case.

The role of 18F-fluoro-2-deoxyglucose positron emission tomography/computed tomography in the management of patients with carcinoma of unknown primary

Purpose

Carcinoma of unknown primary is one of the ten most frequent cancers worldwide. Its median survival time is less than 10 months. Detecting primary tumour locations and/or occult metastatic lesions may inform definitive treatment and improve patients’ prognosis. We aimed to determine: (1) the sensitivity, specificity and accuracy of 18F-fluoro-2-deoxyglucose positron emission tomography/computed tomography; (2) its detection rate of primary tumour locations and occult metastases and (3) factors associated with improved survival times.

Methods

We retrospectively reviewed all cases in the West of Scotland for the period 1 December 2007 to 31 May 2011 that met all our selection criteria: (1) diagnosis of carcinoma of unknown primary; (2) a thorough but negative ‘work-up’ and (3) 18F-fluoro-2-deoxyglucose positron emission tomography/computed tomography report. Statistical methods included frequencies, Kaplan-Meier graphs and log-rank tests to compare survival times.

Results

18F-fluoro-2-deoxyglucose positron emission tomography/computed tomography detected primary tumour sites in 19/51 (37.3%) and occult metastases in 28/51 (54.9%) of eligible patients. Its sensitivity, specificity and accuracy were 79.2%, 70.4% and 74.5%, respectively; 20/51 (39.2%) patients died during the study period with a median survival of 8.4 months (range 21.4, SD ± 6.2). The number of metastatic locations was strongly associated with survival ( p = 0.002), but detection of a primary tumour site ( p = 0.174) or histopathology ( p = 0.301) was not.

Conclusion

18F-fluoro-2-deoxyglucose positron emission tomography/computed tomography detected occult metastatic sites in the majority and a primary cancer location in a substantial minority of patients. Our results were comparable with international literature and may indicate that 18F-fluoro-2-deoxyglucose positron emission tomography/computed tomography have an early role to improve the accuracy of cancer staging and to optimise carcinoma of unknown primary management.

[Usefulness of (18)F-fluorodeoxyglucose-positron emission tomography-computerized tomography in the identification of the primary tumor in patients with cancer of unknown origin]

BACKGROUND AND OBJECTIVE

We determined the utility of the (18)F-fluorodeoxyglucose ((18)F-FDG) positron emission tomography (PET)-computerized tomography (CT) in the localization of the primary tumor in patients with tumor of unknown origin (TUO).

PATIENTS AND METHOD

(18)F-FDG PET-CT scans, performed between November 2006 and November 2010, in search for the primary tumor in patients with TUO, were retrospectively evaluated. Patients underwent a standard PET-CT, 50-60minutes after intravenous injection of 296-370MBq (18)F-FDG. PET-CT studies were assessed as pathological, with/without identification of the primary tumour and no pathological. Final diagnosis was established by histological confirmation and/or clinical/radiologic follow-up longer than 6 months.

RESULTS

We studied 74 patients (59 males, 15 females), with ages ranging from 41-89 years. In 38 (51%) patients the PET-CT assessed the correct origin of the primary tumour. In 8 cases, a histological confirmation in the primary lesion was obtained. In 4 patients the PET-CT showed a false positive result.

CONCLUSION

PET-CT scanning identified 51% of the primary sites in our sample of patients.

Clinical value of whole-body F-18 fluorodeoxyglucose positron emission tomography/computed tomography in patients with carcinoma of unknown primary

INTRODUCTION

The purpose of the study is to investigate the clinical value of F-18 fluorodeoxyglucose positron emission tomography/computed tomography (FDG PET/CT) in detecting the primary sites in patients with carcinoma of unknown primary (CUP).

METHODS

The reports of FDG PET/CT scans of 164 patients with CUP syndrome in consecutive 2589 patients referred to our department from January 2006 to June 2010 were retrospectively reviewed. The final results were obtained from the pathologic reports, other imaging modalities diagnoses and clinical follow-up data.

RESULTS

There were 142 cases in the results analysis, as 19 patients were lost to follow-up and three patients were excluded. FDG PET/CT successfully detected primary tumours in 67 (47.2%) out of 142 patients. Among this group, 53 were pathologically proved and 17 patients were confirmed by clinical follow-up. The primary sites of 38 (56.7%) were in lung, eight (11.9%) in nasopharynx and 13 (19.4%) in digestive system. Six patients were misdiagnosed by FDG PET/CT scan. FDG PET/CT could not detect the primary lesion in 66 patients, and three primary tumours were identified by conventional work-up after negative FDG PET/CT scan. The accuracy, sensitivity and specificity of FDG PET/CT scan in detecting the primary site in this study were 93.7%, 95.7% and 91.7%, respectively. FDG PET/CT scan changed the medical management of about 33.8% of 142 CUP patients.

CONCLUSION

FDG PET/CT whole-body imaging is a valuable tool in detecting the primary tumour of patients with CUP site.

[Cerebral metastasis of a "ghost" bronchopulmonary tumor]

Carcinoma of unknown primary (CUP) is the metastasis of epithelial malignancy whose origin remains unknown. Bronchial carcinoma is the most common cause (45%), however, in more than a quarter of cases, its origin is unknown and the choice of therapy often justifies a histopathological precision brought by the immuno-histochemistry. We present a rare case of cerebral metastasis, revealing an unknown lung cancer after a comprehensive review. This is a patient aged 53 years, chronic smoker, who presented a year and a half ago a sudden loss of consciousness with afebrile tonic-clonic seizure of spontaneous resolution. Clinical examination was unremarkable. Brain imaging by MRI has objectified the presence of two parietal tissue formations, which stereotactic biopsy with histological and immuno-histochemical favored metastasis of lung adenocarcinoma origin. An etiologic in search of the primitive lung remained negative (chest X-ray of face, chest CT and bronchoscopy with sampling upper gastrointestinal endoscopy). The rest of the etiologic, looking for another primitive, remained negative. The diagnosis of a bronchogenic carcinoma with brain metastasis is therefore withheld. The patient received two brain radiotherapies (gamma kniff) with regression of the two nodular formations. We have not given specific treatment and have called for very close monitoring of the patient who remained stable after 18 months. Through this observation, we stress the interest of the histology and immuno-histochemistry of carcinoma of unknown primary (CUP) to the diagnosis, guide therapy and determine prognosis.

Positron emission tomography computed tomography in oncology

The role of positron emission tomography computed tomography in oncological imaging has rapidly evolved. It has proven itself to be cost effective and alters patient management in a significant proportion of cases. This article discusses its current and future applications.

Synthesis and high performance of magnetofluorescent polyelectrolyte nanocomposites as MR/near-infrared multimodal cellular imaging nanoprobes

Here, we describe an easy but robust chemical strategy to synthesize high-performance magnetic resonance (MR)/near-infrared (NIR) multimodal imaging nanoprobes. Poly(γ-glutamic acid) was used for the convenient phase transfer of MnFe(2)O(4) nanoparticles dispersed in organic solvents into aqueous solutions and facilitated further ionic gelation with poly(l-lysine). During the gelation process, MnFe(2)O(4) nanoparticulate satellites were encapsulated in the ionic nanocomplex, which induced synergistic magnetism and resulted in huge T(2) relaxivity (r(2)). The positively charged outer surfaces were assembled with other negatively charged NIR emitting fluorescent nanocrystals and enabled the highly efficient delivery of the magnetofluorescent polyelectrolyte nanocomposites (MagFL-PEN) into cancer cells. The enhancement of negative contrast of MagFL-PEN at 2 μg/mL concentration was similar to that of Resovist at 20 μg/mL concentration. The NIR fluorescence microscopy images of the MagFL-PEN-labeled cells even at 12.5 pM were able to be clearly observed. The labeling efficiency of MagFL-PEN was approximately 65-fold higher compared to that of the commercialized fluorescent nanocrystals, only after 3 h incubation period, even at the test concentration (100 pM). Due to the high-performance capabilities both in materials properties and cell labeling efficiency, the MagFL-PEN is expected to be used as a highly efficient MR/NIR dual-modality imaging nanoprobe in the detection of cancer cells and monitoring of therapeutic cells in vivo.

The frequency and spectrum of thymus 2-[fluorine-18] fluoro-2-deoxy-D-glucose uptake patterns in hyperthyroidism patients

RATIONALE AND OBJECTIVES

Thymic hyperplasia is associated with hyperthyroidism. Increased thymus 2-[fluorine-18]fluoro-2-deoxy-D-glucose (FDG) uptake in hyperthyroidism patients has been reported. The aim of this study was to analyze the FDG positron emission tomography (PET) thymus uptake spectrum in patients with active hyperthyroidism with correlation with serum hormones.

MATERIALS AND METHODS

The prospective study included FDG PET scans from 65 hyperthyroidism patients and 30 subjects with euthyroid status as control group. The intensity of FDG uptake in thyroid and thymus regions was graded subjectively on a five-point scale and semi-quantitatively by measuring standard uptake value (SUV). Correlation coefficient between thymus SUV and serum thyroxine, triiodothyronine, thyrotropin, thyroid peroxidase antibodies (TPO Ab), thyrotropin receptor autoantibody (TR Ab), and thymulin were analyzed.

RESULTS

Among 65 hyperthyroidism patients, 30 (46.2%) and 39 (60%) patients showed thyroid and thymus FDG uptake, respectively. The frequency of thymus uptake FDG was high in patients younger than age 40 (28/31, 90.3%). The patterns of the thymic FDG uptake include inverted V or triangular, separated triangular, united nontriangular, unilateral right or left extension, and focal midline. Focal midline FDG uptake was the most common pattern (15/39, 38.5%). None of the control group showed thymus FDG uptake. The correlation coefficient between the FDG uptake SUV levels in thymus and serum hormones, thyrotropin, TPO Ab, TR Ab, and thymulin levels were all low (P > .05).

CONCLUSIONS

In FDG PET scan, thymus activity was common in hyperthyroidism patients; this should not be misdiagnosed as a malignancy in patients exhibiting weight loss.

Lymph node metastasis of squamous cell carcinoma from an unknown primary in the upper and middle neck: Impact of (18)F-fluorodeoxyglucose positron emission tomography/computed tomography

PURPOSE

The purpose of this study was to assess the potential of (18)F-fluorodeoxyglucose positron emission tomography/computed tomography (FDG-PET/CT) imaging for detection of the primary tumor and its impact on treatment planning in patients presenting with cancer of unknown primary and squamous cell carcinoma (SCC)-positive cervical lymph nodes of the upper and middle neck.

METHODS

The study population consisted of 18 consecutive patients with biopsy-proven SCC involving lymph nodes of the upper and middle neck region and negative conventional diagnostic procedures with regard to the location of the primary. All patients underwent FDG-PET/CT according to a standard procedure in search for the primary, unidentified tumor.

RESULTS

In none of the patients FDG-PET/CT was able to indicate a primary tumor localization. Although FDG-PET/CT did identify all sites of known lymph node involvement, neither additional sites of lymph node involvement nor sites of distant metastases were identified. Accordingly, FDG-PET/CT did not impact patient treatment planning.

CONCLUSIONS

In this series, including patients suffering from lymph node metastases by an SCC of unknown primary in the upper and middle neck, FDG-PET/CT was unable to identify a primary tumor. In addition, FDG-PET/CT did not modify the treatment planning in any of the patients studied.

18F-FDG PET/CT as a diagnostic tool in patients with extracervical carcinoma of unknown primary site: a literature review

BACKGROUND

Carcinoma of unknown primary (CUP) represents a heterogeneous group of metastatic malignancies for which no primary tumor site can be identified after extensive diagnostic workup. Failure to identify the primary site may negatively influence patient management. The aim of this review was to evaluate (18)F-fluorodeoxyglucose positron emission tomography/computed tomography ((18)F-FDG PET/CT) as a diagnostic tool in patients with extracervical CUP.

MATERIALS AND METHODS

A comprehensive literature search was performed and four publications were identified (involving 152 patients) evaluating (18)F-FDG PET/CT in CUP patients with extracervical metastases. All studies were retrospective and heterogeneous in inclusion criteria, study design, and diagnostic workup prior to (18)F-FDG PET/CT.

RESULTS

(18)F-FDG PET/CT detected the primary tumor in 39.5% of patients with extracervical CUP. The lung was the most commonly detected primary tumor site (∼50%). The pooled estimates of sensitivity, specificity, and accuracy of (18)F-FDG PET/CT in the detection of the primary tumor site were 87%, 88%, and 87.5%, respectively.

CONCLUSIONS

The present review of currently available data indicates that (18)F-FDG PET/CT might contribute to the identification of the primary tumor site in extracervical CUP. However, prospective studies with more uniform inclusion criteria are required to evaluate the exact value of this diagnostic tool.

Detection of primary sites in unknown primary tumors using FDG-PET or FDG-PET/CT

Background

Carcinoma of unknown primary tumors (CUP) is present in 0.5%-9% of all patients with malignant neoplasms; only 20%-27% of primary sites are identified before the patients die. Currently, 18F-fluorodeoxy-glucose positron-emission tomography (18F-FDG PET) or PET combined with computed tomography (PET/CT) is widely used for the diagnosis of CUP. However, the diagnostic yield of the primary site varies. The aim of this study was to determine whether PET or PET/CT has additional advantages over the conventional diagnostic workup in detecting the primary origin of CUP.

Findings

Twenty patients with unknown primary tumors that underwent PET or PET/CT were included in this study. For all patients, the conventional diagnostic workup was unsuccessful in detecting the primary sites. Among 20 patients, 11 had PET scans. The remaining nine patients had PET/CT. In all 20 patients, neither the PET nor PET/CT identified the primary site of the tumor, including six cases with cervical lymph node metastases. The PET and PET/CT revealed sites of FDG uptake other than those associated with known metastases in seven patients, but these findings did not influence patient management or therapy. Two patients had unnecessary invasive diagnostic procedures due to false positive results on the PET or PET/CT.

Conclusions

Although it is inconclusive because of small sample size of the study, the additional value of PET or PET/CT for the detection of primary sites in patients with CUP might be less than expected; especially in patients that have already had extensive conventional diagnostic workups. Further study is needed to confirm this finding.

Unknown primary tumors

An unknown primary tumor (UPT) is defined by the presence of a metastatic cancer without a known primary site of origin despite a standardized diagnostic workup. Clinically, UPTs show rapid progression and early dissemination, with signs and symptoms related to the metastatic site. The molecular bases of their biology remain largely unknown, with no evidence as to whether they represent a distinct biological entity. Immunohistochemistry remain the best diagnostic tool in term of cost-effectiveness, but the time-consuming "algorithmic process" it relies on has led to the application of new molecular techniques for the identification of the primary site of UPTs. For example, several microarray or miRNA classifications of UPTs have been used, with an accuracy in the prediction of the primary site as high as 90%. It should be noted that validating a prediction of tissue origin is challenging in these patients, since most of them will never have a primary site identified. Moreover, prospective studies to determine whether selection of treatment options based on such profiling methods actually improves patient outcome are still missing. In the last few years functional imaging (i.e. FDG-PET/CT) has gained a main role in the detection of the site of origin of UPTs and is currently recommended by the European Association of Nuclear Medicine. However, despite recent refinements in the diagnostic workup, the site of origin of UPT often remains elusive. As a consequence, treatment of patients with UPT is still empirical and inadequate.

Asymptomatic primary fallopian tube cancer: an unusual cause of axillary lymphadenopathy

Primary Fallopian tube malignancy is considered a rare disease and is often mistaken histologically and clinically for ovarian cancer. The etiology is poorly understood, and it typically presents at an advanced disease stage, as symptoms are often absent in the initial period. As a result, primary fallopian tube cancer is generally associated with a poor prognosis. We present the case of a 45-year-old female who presents with a 5-day history of left axillary swelling and a normal breast examination. Mammogram and biopsy of a lesion in the left breast revealed a fibroadenoma but no other abnormalities. Initial sampling of the axillary node was suspicious for a primary breast malignancy, but histology of the excised node refuted this. PET-CT showed an area of high uptake in the right pelvis, and a laparoscopy identified a tumor of the left fallopian tube which was subsequently excised and confirmed as a serous adenocarcinoma.

Gastrointestinal cancer educational case series: management of metastatic adenocarcinoma of unknown primary origin in a Ph+ ALL survivor

INTRODUCTION

Secondary malignancies and chronic end-organ sequelae are significant and steadily rising consequences of cancer therapy. The workup and management of a carcinoma of unknown primary must consider the patient's clinical presentation, radiologic and pathologic findings, and comorbidities.

CASE REPORT

We present the case of a 50-year-old female survivor of Philadelphia chromosome-positive acute lymphoblastic leukemia (Ph+ ALL) with significant treatment-related end-organ sequelae who developed a metastatic adenocarcinoma of unknown primary 15 years following curative therapy for her ALL. The complex management issues related to the investigations and choice of therapy for this patient are reviewed.

DISCUSSION

This case discusses key issues related to the workup and management of a carcinoma of unknown primary. In addition, it illustrates the importance of taking patient comorbidities into consideration and tailoring investigations and therapy accordingly.