Review Article
Occult Breast Cancer: A Diagnostic Dilemma. Case Report and Literature Review
Sanaz Ghafouri* and Alexandra Drakaki
UCLA Medicial Center, USA
*Corresponding author: Sanaz Ghafouri, UCLA Medical Center, 757 Westwood Plaza, Los Angeles, 90095, CA, USA
Published: 17 Jul, 2018
Cite this article as: Ghafouri S, Drakaki A. Occult Breast
Cancer: A Diagnostic Dilemma. Case
Report and Literature Review. Ann Clin
Case Rep. 2018; 3: 1536.
Abstract
Background: Occult breast cancer, or histologically-proven breast cancers without an identifiable
primary breast cancer, is a rare disease. It remains challenging for clinicians to diagnose and treat
it as there are currently no standardized diagnostic or treatment approach to patients with occult
breast cancers.
Patient Description: We report a case of a 59-year-old female with dyspnea and increased
oxygen requirements, who on further investigation was found to have pulmonary lymphangitic
carcinomatosis, axillary and supraclavicular lymphadenopathy, which was ultimately diagnosed
as hormone positive occult breast cancer. She responded well to palliative hormone therapy and
returned to baseline functional status and to breathing on room air.
Conclusion: This case is a unique and unusual presentation of breast cancer that highlights the
importance of recognizing that primary malignancies of unknown origin do exist. In this case, the
patient was fortunate enough both to have her malignancy discovered early based on symptoms
of metastasis and to have hormone positive disease that is more responsive to palliative endocrine
therapies. However, there needs to be a clearer approach to diagnosing and treating occult breast
cancers.
Introduction
Occult Breast Cancer (OBC), defined as histologically-proven breast cancer detected outside of
the breast without an obvious primary breast tumor, remains a diagnostic and therapeutic challenge
for many oncologists. Fortunately, OBC is a rare entity, accounting for only 0.1% to 0.8% of newly
diagnosed breast cancers [1].
We present a case of occult breast cancer in a patient who presented with shortness of
breath and hypoxemia requiring oxygen supplementation, approaching but ultimately avoiding
intubation. The patient was found to have pulmonary lymphangitic carcinomatosis with axillary
and supraclavicular lymphadenopathy. Biopsy of the supraclavicular lymph node revealed hormone
receptor positive, HER2 negative invasive ductal adenocarcinoma without any primary breast mass.
She was ultimately treated as OBC with hormone therapy alone. Interestingly, four years later she
continues to show response to therapy, without clinical evidence of disease, despite her initially
predicted poor prognosis.
Case Presentation
A 59-year-old female immigrant from Guatemala presented to the hospital with two months
of progressively worsening cough and shortness of breath. CT angiogram of the chest showed
abnormalities of the lung field, concerning for atypical infection versus lymphangitic carcinomatosis
of unknown primary. PET-CT confirmed these lung findings, but also revealed right axillary and
supraclavicular lymphadenopathy.
She underwent biopsy of the right supraclavicular lymph node that was consistent with
adenocarcinoma, concerning for breast cancer primary that was ER positive, PR positive, HER-2
negative, CK7 negative, and GATA3 positive. Tumor markers were checked at the time and she
was found to have an elevated CA-125 at 116 units/ml (normal levels below 35 units/ml). Given the
critical presentation and the need for oxygen, she underwent bronchoscopy and bronchoalveolar
lavage. Interestingly that showed mycobacterium avium complex infection as well, for which she
was started on Clarithromycin, Ethambutol, and Rifabutin. During that hospitalization, her ECOG
performance status was a 3, and given her poor prognosis and inability to tolerate chemotherapy the patient was considering palliative care approach and eventually
hospice.
She was ultimately discharged from the hospital with home
oxygen and oncology follow up. Given that no primary mass was
identified in the initial staging imaging, patient had an MRI of the
breasts as well as a mammogram that interestingly enough were both
normal. She was started on an Aromatase Inhibitor (AI) as she was
postmenopausal and within the first few weeks she had significant
response on imaging, as well as clinically, with discontinuation of
oxygen use and decreasing of her CA-125. After discussing different
treatment options, mastectomy was deferred based on the fact that
she had spread to the lungs and no obvious primary on presentation.
She completed the course of antibiotics for her mycobacterial
infection and continued to show improvement with hormone
therapy for years after diagnosis. She had to transition from the
non-steroidal AI anastrozole to exemestane due to arthralgias. After
three years being on treatment with antiestrogen therapy, a staging
CT chest showed some evidence of progression along with rising CA
125, and thus, she was transitioned to the novel combination of the
antiestrogen Fulvestrant and the CDK4/6 inhibitor Palbociclib. She
has been on this combination for one year, and is doing well, except
the expected side effects of neutropenia. Her ECOG performance
status has returned from a 3 to a 0, she is off home oxygen and her
initially suspected poor prognosis was surprisingly invalidated.
Discussion
Occult breast cancers can be a diagnostic enigma to oncologists,
and warrant comprehensive immunohistochemical staining of the
tissue that is biopsied, clinical breast examination and mammography
or breast MRI to support the diagnosis of a breast primary. When the
clinical exam, mammogram and breast MRI do not show evidence of
a primary breast malignancy, the diagnosis tends to be favored based
on histologic patterns from the tissue of interest. Positive staining
for CK7, ER, PR, mammaglobin, and GATA3 favors the diagnosis
of breast cancer, which aside from the negative CK7, was consistent
for our patient. HER-2 immunostaining, though it lacks specificity
and is only over-expressed in about 18% to 20% of all breast cancers,
remains a routine component of the comprehensive tissue staining
for OBC, given that there exists effective targeted treatment of HER-2
positive OBC [2,3].
Given the rare nature of OBC, there is no standardized treatment
approach. Per the NCCN guidelines, treatment for OBT or Tx Node
positive breast cancers, which is considered stage III by 8th edition
of American Joint Committee on Cancer (AJCC) guidelines, include
mastectomy with Axillary Lymph Node Dissections (ALND) with or
without post-mastectomy radiation or simply ALND with radiation
[4]. Furthermore, according to the American Society of Breast
Surgeons, mastectomy is the most common treatment for OBC (47%),
followed by breast radiation (37%) [5]. However, in this case report,
the patient not only had metastasis to the lymph nodes but also had
pulmonary involvement and poor performance status, and thus, was
considered stage IV at diagnosis, in which case, the treatment is the
same as for non-OBC metastatic breast cancer.
Moreover, Ping et al. [6] compared the demographics and cancer
characteristics between OBC and non-OBC and found that OBC
patients were significantly older than those with non-OBC, and
estrogen receptor positive rates in OBC were lower, which would
typically portend poorer prognosis. By retrospectively analyzing
93 OBC cases and 1576 non-OBC cases between the years of 1980
and 2005, the authors found that the median age for OBC and non-
OBC patients was 54 and 48, respectively, which was proven to be
statistically significant. There was significantly lower ER positivity,
which was 46.2% of OBC cases compared to 56.6% of non-OBC
cases; however, there were no significant differences in PR positivity.
Furthermore, the authors compared OBC and non-OBC stages I, II,
and III and found that the 5- and 10- year survival rates for OBC
was comparable to stage III non-OBC cases at about 51% and 43%
for 5- and 10- year survivals, respectively. Additionally, Wang et al.
[6,7] compared PR positive and PR negative OBC patients and found
that the former had statistically significant better overall survival and
lower recurrence rates, suggesting that progesterone positivity is an
important prognostic feature for OBC.
Regardless of the similar prognosis between OBC and stage III
non-OBC disease, this patient presented as stage IV metastatic breast
cancer at the time of diagnosis, and the data is currently lacking
whether there is a difference in overall survival and progression
free survival for patients with metastatic occult breast cancer
versus metastatic non-occult breast cancer. Typically, patients with
metastatic lymphangitic pulmonary disease tend to have shorter
progression free disease and overall survival however a significant
cofounder in her case was the fact that she had an underlying infection
that compromised her respiratory status at presentation [8].
Serum tumor markers commonly associated with breast cancer
include CA 15-3, CA 27.29 and CEA, and these serve prognostic value
to clinicians when monitoring response to treatment in patients with
metastatic disease. However, interestingly, this patient had an elevated
CA-125 on presentation, which is most commonly associated with
ovarian cancer, though elevated levels have been seen in 84% of cases
of metastatic breast cancer [9]. Additionally, studies have shown that
an increased CA-125 is associated with metastasis to the lungs or
pleura and is related to poor prognosis [10].
Fortunately, this patient had hormone positive OBC that
responded to the standard first line treatments for stage IV hormone
positive HER-2 negative breast cancers, which are the Aromatase
Inhibitors (AI). AIs have proven to have increased overall survival and
more tolerability compared to other hormone therapies, particularly
in post-menopausal women [11]. However, her disease eventually
progressed despite the first line AI, and she was transitioned to one of
the second line therapies, which include combination anti-estrogen
Fulvestrant and CDK4/6 inhibitor Palbociclib.
CDK4/6 inhibition in combination with anti-estrogen therapy
has shown promising results for patients with hormone positive
metastatic breast cancer and is becoming recognized as a first line
alternative to AI alone. According to the Paloma II trial, a phase 3 study
comparing Palbociclib and Letrozole to Letrozole and placebo, there
was a statistically significant difference in the median progressionfree
survival, of 24.8 months and 14.5 months, respectively [12].
Moreover, the results from the study were remarkable, nearly doubling
the duration of progression-free survival for metastatic breast cancer.
Additionally, the phase III MONALEESA-3 trial comparing patients
with advanced hormone positive breast cancer on Fulvestrant and
Ribociclib, another CDK4/6 inhibitor, to Fulvestrant alone, reported
a median progression-free survival of 20.5 months and 12.8 months,
respectively, representing over 40% reduction in the risk of disease
progression, which shows in our patient’s impressive response to the
treatment regimen [13].
Conclusion
In conclusion, the rare entity of OBC still has much research to be done in order to develop standardized diagnostic and treatment approaches that can be used for our patients. Fortunately, this patient’s pulmonary symptoms from her MAC infection and possibly from her pulmonary metastasis, led to an earlier diagnosis of OBC. While advanced at the time of diagnosis, her hormone positive disease was a favorable prognostic feature, and she was responsive to palliative endocrine therapy, impressively able to regain her baseline prior-to-cancer functional status.
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