Breast lymphoma
DLBC lymphoma is an NHL that usually presents with a rapidly enlarging mass. Systemic B symptoms (that is fever and weight loss >10% of body weight) may occur in approximately 30% of patients [
5]. Large B-cell lymphoma is the most common type of NHL; its prevalence is about 30% of all NHL patients. Also, large B-cell lymphoma accounts for approximately 40% of patients with extra-nodal NHL [
2,
6]. Extra-nodal sites may be of lung, pleura, thymus, breast, spleen, liver, pancreas, musculoskeletal system, or central nervous system [
2]. Primary breast lymphoma is a rare disease and presented only 0.1% of the more than 25,000 primary malignant tumors of the breast treated during a 30-year period in a single institution [
6].
There are only a few reports of FDG-PET findings of extra-nodal breast lymphoma [
7‐
10]. Kumar
et al. reported the findings of FDG-PET in a case of a patient with DLBC lymphoma that presented as intense and diffuse FDG uptake in dense breast tissue and was not detectable by diagnostic CT [
7]. Bakheet
et al. reported a patient with breast lymphoma mass that had intense FDG uptake in the rim and photopenic center suggestive a tumor with central necrosis [
8]. Nihashi
et al. described the FDG uptake as intense, round and homogeneous, but, unfortunately, there were no CT images for correlation [
9]. Another case reported a patient with concurrent breast lymphoma and multiple nodular adenosis [
10]. In that case, an FDG PET scan after one cycle of chemotherapy showed diffuse moderate FDG uptake in the right breast which might have reflected good response to therapy based on FDG intensity. In the current case, a large, intensely FDG avid, hyperdense tumor mass infiltrated almost the entire soft tissue of the left breast which was not described previously. In addition, the FDG avid lymph nodes in the ipsilateral axillary and internal mammary regions showed a metastatic pattern similar to that of typical metastatic breast cancer. These findings have not been reported in the literature.
The role of FDG PET in the diagnosis, staging and restaging of lymphoma has been established [
2,
11]. Integrated PET/CT increases the sensitivity and specificity compared to FDG PET alone. In Hodgkin's lymphoma or high-grade NHL, the sensitivity of PET/CT and contrast-enhanced CT for lymph node involvement was found to be 94% and 88%, respectively, while the specificity was 100% and 86%, respectively [
11]. For extra-nodal disease, PET/CT and contrast-enhanced CT had a sensitivity of 88% and 50%, and a specificity of 100% and 90% [
11]. The degree of FDG uptake can distinguish indolent from aggressive NHL [
12]. An SUV >10 was found to have high likelihood for aggressive disease. In our patient, SUV was 21 in the breast mass and there was associated locoregional lymphadenopathy suggestive of aggressive disease. Early FDG PET/CT scan can be carried out after first-line chemotherapy to increase the prognostic value by assessing the degree of interval SUV decrease, with event-free survival improving from 65% to 76% in patients with DLBC lymphoma when quantitative SUV analysis was added to a visual assessment [
13].
The Ann Arbor staging system developed in 1971 for Hodgkin's lymphoma was adapted for staging of NHL [
14]. Based on the present FDG PET/CT findings, our patient had stage II disease because there was involvement of two lymph node regions on the same side of the diaphragm besides the primary breast lesion.
Cervical cancer
The incidental detection of a second malignancy in cancer patients undergoing FDG PET/CT staging is not uncommon [
15]. However, the FDG PET/CT scan diagnosed a rare case of concurrent breast lymphoma and cervical cancer that has never been reported in the literature. It seems unlikely, though, that the breast lymphoma and the cervical cancer of our patient are caused by one or the other.
The International Federation of Gynecologists and Obstetricians (FIGO) in collaboration with the World Health Organization (WHO) and the International Union Against Cancer (IUCC) are the most common staging systems for cervical cancer [
16]. The FIGO staging system is largely based upon physical examination. Thus, a good pelvic examination is important. Tumor size and parametrial involvement are best assessed by rectovaginal examination. Colposcopy, cystoscopy, and proctoscopy can be used to assess adjacent areas. Optional procedures include ultrasound, CT, magnetic resonance imaging (MRI), and FDG PET or PET/CT, and can be of value for treatment planning.
FDG PET has been used in initial staging and monitoring of therapy in patients with cervical cancer [
17]. In a review article, the sensitivity and specificity for pelvic involvement with newly diagnosed cervical cancer were 79% and 99% for FDG-PET, and 72% and 96% for MRI; for CT the sensitivity was 47%, the specificity could not be accurately determined. For para-aortic node metastasis, FDG-PET had a sensitivity of 84%, and a specificity of 95% [
17]. The diagnostic accuracy of FDG PET in lymph node staging, however, might be lower in women with early stage diseases [
18]. This is partly attributed to the low-dose and unenhanced CT of the PET/CT scan that is sub-optimal for detecting sub-centimeter nodal disease. Of note, the CT was sub-optimal in the current patient as well. But PET/CT scan is increasingly being carried out with intravenous contrast media.
In our patient, FDG PET/CT findings suggested a T2 tumor that involved the proximal third of the vagina and the corpus uterine. There was no evidence of parametrial tumor invasion. An intensely FDG avid soft tissue density seen in the left pelvis was thought to be either lymph node metastasis or physiologic ovarian FDG uptake. Subsequent ultrasound and diagnostic contrast-enhanced CT confirmed the presence of a corpus luteal cyst that sometimes may cause false-positive interpretation because of the FDG avidity [
19]. Based on imaging findings, the cervical cancer was T2N0M0, stage II. The degree of FDG uptake has prognostic significance in cervical cancer and was found to negatively correlate with treatment response and prognosis [
20].