Small-cell neuroendocrine carcinoma of the breast

Evolution of an invasive ductal carcinoma to a small cell carcinoma of the breast: A case report

RATIONALE

Small cell carcinoma (SCC) is a rare subtype of breast cancer and presents a complex diagnostic and treatment challenge, due to paucity of data. To the best of our knowledge, most cases of breast SCC reported in the literature describe a de novo breast primary. Our case is unique as it describes the evolution of an invasive ductal carcinoma after treatment into a SCC of the breast.

PATIENT CONCERNS AND DIAGNOSIS

We report a case of a 53-year-old female, lifelong non-smoker, who initially presented with breast mass noted on self examination. Breast and axillary lymph node biopsy demonstrated a hormone receptor positive invasive ductal carcinoma with a metastatic T3 lesion.

INTERVENTION

She was treated with first-line palbociclib/letrozole with initial clinical response, and at progression was switched to capecitabine with no response. Repeat biopsy of the axillary lesion showed evolution of the tumor into a triple negative breast cancer. She was then treated with third-line paclitaxel and radiation therapy with good initial response. She eventually had further disease progression and presented with a new mediastinal lymphadenopathy causing SVC syndrome. Biopsy of this showed a small cell variant of breast neuroendocrine carcinoma. Due to the evolution of histology in this case, a retrospective review of her initial breast specimen as well as the second biopsy from the axilla was conducted which confirmed that the mediastinal lymphadenopathy was metastatic from the original breast tumor.

OUTCOMES AND LESSONS

We speculate that the initial treatment allowed a minority of treatment-resistant neuroendocrine cells to grow and become the dominant face of the tumor. Our patient had an excellent response to carboplatin/etoposide and consolidative locoregional radiotherapy but presented with an early intracranial recurrence. This is a similar pattern of metastases as seen in lung SCC and highlights a potential role for prophylactic cranial irradiation in breast SCC. Further studies are needed to better understand the biology and treatment of breast SCC which continues to present a challenge for clinicians.

Primary neuroendocrine carcinoma of the breast: report of 2 cases and literature review

Neuroendocrine tumors of the breast are very rare accounting for less than 0.1% of all breast cancers and less than 1% of all neuroendocrine tumors. Focal neuroendocrine differentiation can be found in different histologic types of breast carcinoma including in situ and invasive ductal or invasive lobular. However, primary neuroendocrine carcinoma of the breast requires the expression of neuroendocrine markers in more than 50% of the cell population, the presence of ductal carcinoma in situ, and the absence of clinical evidence of concurrent primary neuroendocrine carcinoma of any other organ. Reports discussing the imaging characteristics of this rare carcinoma in different breast imaging modalities are scarce. We present 2 cases of primary neuroendocrine carcinoma of the breast for which mammography, ultrasound, and magnetic resonance imaging findings and pathology findings are described. A review of the medical literature on this particular topic was performed, and the results are presented.

68Ga DOTANOC PET/CT in primary neuroendocrine tumor of the breast

Primary neuroendocrine tumor (NET) of the breast is very rare. We present a case of a pathologically confirmed, primary breast NET in a 49-year-old woman with 68Ga DOTANOC PET/CT imaging findings. 68Ga DOTANOC PET/CT revealed somatostatin receptors expressing active lesions in primary right breast NET with metastases to multiple bilateral axillary and right cervical lymph nodes, bilateral lungs, and multiple skeletal sites.

Imaging features of extrapulmonary small cell carcinoma

Small cell carcinoma accounts for approximately 20% of lung cancers; however, it rarely occurs at other sites. Extrapulmonary small cell carcinoma (EPSCC) is notoriously aggressive with a strong propensity for both regional and distant spread. The majority of the literature on these uncommon tumours is from a clinicopathological viewpoint with a relative paucity of detail regarding the radiological findings. This review will focus on the imaging features of EPSCC in its predominant sites of origin: the gastrointestinal tract, genitourinary tract, head, neck, and breast. We will also discuss the role of positron-emission tomography (PET)/computed tomography (CT) in the staging of EPSCC.

Primary neuroendocrine tumor of the breast: imaging features

Focal neuroendocrine differentiation can be found in diverse histological types of breast tumors. However, the term, neuroendocrine breast tumor, indicates the diffuse expression of neuroendocrine markers in more than 50% of the tumor cell population. The imaging features of neuroendocrine breast tumor have not been accurately described due to extreme rarity of this tumor type. We present a case of a pathologically confirmed, primary neuroendocrine breast tumor in a 42-year-old woman, with imaging findings difficult to be differentiated from that of invasive ductal carcinoma.

Two cases of primary small cell carcinoma of the breast showing non-mass-like pattern on diagnostic imaging and histopathology

Primary small cell carcinoma of the breast is a rare breast cancer. We report two cases of this entity showing a non-mass-like pattern on multimodality images and histopathology. Both women presented with a breast mass, and one had axillary lymphadenopathy. Both cases revealed fine calcification on mammography (MMG) and an irregularly shaped, hypoechoic lesion on ultrasonography. Computed tomography (CT) and magnetic resonance imaging (MRI) showed non-mass-like enhancement in both cases. Dynamic MRI showed medium initial enhancement followed by persistent delayed enhancement in one patient, whereas rapid initial enhancement with plateau delayed enhancement was observed in the other. The breast lesions showed very high signal intensity on diffusion-weighted MRI. Positron emission tomography showed moderate accumulation of 2-fluoro-2-deoxyglucose in the breast tumor and lymph node metastasis. The non-mass-like enhancement on CT and MRI and the segmental fine calcification on MMG indicate the abundance of components of ductal carcinoma in situ and the breast origin of the small cell carcinoma.