Keywords:
Neoplasm Metastasis - PROSTATE - LUNG.
Descritores:
68 Ga-PSMA - Metástase de tumor-para-tumor - Câncer de próstata - Câncer de pulmão.
INTRODUCTION
“Tumor-to-tumor metastasis” is a rare phenomenon, described in few reports in the
literature, in which a tumor metastasizes and its growth is established in another
tumor.[1] Lung carcinoma is the most frequent donor tumor, but it is extremely rare as recipient.[2] In this report we describe, for the first time, a case of this combination of donor
and recipient tumors: metastasis from prostatic adenocarcinoma to lung adenocarcinoma.
Histological analysis was conducted after68 Ga-PSMA PET-CT found evidence of pulmonary nodules in a patient with a diagnosis
of prostate cancer undergoing restaging after biochemical relapse.
PRESENTATION OF THE CASE
The patient was an 89-year-old male with previous low charge of smoking (less than
10 years-package) and who had been diagnosed in 2005 with adenocarcinoma of the prostate,
graded at Gleason 8 (4+4), and underwent radical prostatectomy the same year. In 2009,
biochemical and local relapse were detected and he was treated with salvage radiotherapy
combined with hormone therapy. In July 2018, biochemical relapse was detected again
with PSA level raising from 2.79 to 3.84 plus lung lesions in a castrationresistant
scenario and it was started abiraterone acetate as systemic treatment. The68 Ga-PSMA PET-CT imaging was used for restaging, revealing anomalous tracer concentrations
in the prostatic space, with an SUV of 2.6; in a left peribronchial mass, with an
SUV of 8.0; and in multiple bilateral pulmonary nodules with SUVs ranging from 2.8
to 4.4. ([Images 1], [2] and [3]).
A biopsy was then performed on one of the nodules in the patient's left lung ([Image 4]). Three fragments were obtained from a transthoracic core biopsy and all of them
showed malignant epithelial cells infiltrating a desmoplastic stroma, arranged in
a predominant acinar pattern, with focal cribriform structures ([Images 5A] and [5B]). Since the patient had a history of prostate cancer, an immunohistochemical study
was performed. Most of the malignant glands stained diffusely positive for TTF-1 (nuclear
staining) ([Image 5C]) and Napsin-A (granular cytoplasmic) ([Image 5D]), both markers of pulmonary adenocarcinoma. There was a small group of acini that
were negative for these markers. These glands were positive for NKX3.1 (nuclear staining)
([Image 5E]) and PSA (granular cytoplasmic) ([Image 5F]), indicating prostatic origin. Taking all these findings into account, the final
diagnosis was metastatic prostatic adenocarcinoma within a lung adenocarcinoma (tumor-to-tumor
metastasis). It was proposed maintenance with current hormone therapy for prostate
cancer and driven-mutation test for target therapy against lung cancer.
Image 1. Full body image at maximum intensity projection (MIP) from the PET-CT examination,
demonstrating areas of abnormal 68Ga-PSMA concentration in the lungs, especially the
left lung nodule that was biopsied (cross).
Image 2. Axial slices from low dose CT (on the left) and coregistered PET-CT (on the right)
demonstrating 68Ga-PSMA concentrations in the prostate space with an SUV of 2.6.
Image 3. Coregistered PET-CT axial slices (on the left) and coronal slices (on the right)
demonstrating 68Ga-PSMA concentrations in the left lung nodule (which was later biopsied)
with an SUV of 4.7.
Image 4. Axial computed tomography slices guiding the biopsy of left lung nodule using a large
caliber needle with a Coaxial 17 / 18 G system and automatic trigger device.
Image 5. A) Biopsy fragments showing an infiltrating adenocarcinoma (H&E, 40x). B) The tumor
was composed of acinar and cribriform malignant glands (H&E, 100x). Most of the tumor
cells were positive for TTF-1 (C, 100x) and Napsin-A (D, 100x), but a small group
of cells were negative for both markers (upper left corner). In contrast, those glands
were positive for NKX3.1 (E, 100x) and PSA (F, 100x), mirroring the images from the
lung markers and confirming the diagnosis of a metastatic prostatic adenocarcinoma
inside a primary lung tumor.
DISCUSSION
“Tumor-to-tumor metastasis” is a phenomenon that is still considered rare in the literature
and, according to Campbell et al., certain criteria must be met for diagnosis: more
than one primary tumor; the recipient tumor must be a true benign or malignant neoplasm;
metastatic growth must be established in the recipient tumor; and tumors that have
metastasized to the lymphatic system are excluded.[3]
Just as there are differences in metastatic potential between different tumors, there
are also differences in their capacity to host metastases. According to the literature,
clear cell renal cell carcinoma is the most common metastasis recipient tumor, followed
by sarcoma, meningioma, and thyroid cancer. Lung carcinoma is the most common donor
tumor (40-50% of cases), followed by breast, gastrointestinal tract, prostate, and
thyroid carcinomas.[4]
Lung carcinoma as recipient of tumor metastasis, as described in this case, is one
of the rarest presentations. The most common donor tumor for this recipient is papillary
thyroid carcinoma. In addition to not affording a rich network of blood vessels, they
tend to grow rapidly and do not provide a suitable host environment.[2] Moreover, prostatic metastasis to normal pulmonary parenchyma, in the absence of
other metastatic sites, is itself a rare finding.[5]
Applications for68 Ga-PSMA PET-CT continue to extend beyond prostate cancer. Expression of PSMA has
been demonstrated by immunohistochemistry in neovasculature of a range of lung tumors
that exhibited affinity with68 Ga-PSMA. However, this analytical method is not yet able to discriminate reliably
between pulmonary lesions in patients with prostate cancer. Primary lung tumors have
demonstrated similar tracer concentrations to prostatic metastases, creating a diagnostic
challenge that, in the majority of cases, still requires histological confirmation.[6]
Ethical Considerations: This case report received approval from the institution's
Research Ethics Committee.
Conflict of Interest Statement: The authors declare that the research was conducted
in the absence of any commercial or financial relationships that could be construed
as a potential conflict of interest.
Bibliographical Record
André Marcondes Braga Ribeiro, Ana Luiza Tatarin Vivan, Eduardo Nóbrega Pereira Lima,
Maria Nirvana da Cruz Formiga, Mauro Daniel Spina Donadio, Felipe D'Almeida Costa.
Pulmonary Metastasis of a Prostate Adenocarcinoma within a Primary Lung Adenocarcinoma:
A Tumor-totumor Metastasis Case Report. Brazilian Journal of Oncology 2019; 15: e-20190010.
DOI: 10.5935/2526-8732.20190010
