Primary neuroendocrine carcinoma of the breast: a rare presentation and review of the literature

Abstract

Primary neuroendocrine carcinoma of the breast (NEBC) is a very rare occurrence accounting for less than 0.1% of all breast cancers. Typically, the tumor presents with ER- and PgR-positive and HER-2-negative status. Despite its luminal type, NEBC is associated with a more aggressive clinical course and poorer prognosis compared to the other types of invasive breast cancer. Clinical and radiological findings are nonspecific. The most common clinical manifestation is a palpable mass whereas in mammography the tumor most commonly appears as a round or oval mass without spiculated margins. Herein, a very rare case of NEBC is described in an asymptomatic patient who presented with an area of architectural distortion and the presence of microcalcifications that was incidentally detected on a screening mammography. A review of the literature has also been conducted. The diagnosis of NEBC requires a thorough investigation to exclude the possibility of a metastatic neuroendocrine tumor from another site because the two entities require different treatment approaches. Due to the rarity of the disease, the optimal therapeutic approach has not been clearly defined. Surgical resection is the mainstay of treatment. Further research is needed to better understand the molecular characteristics of NEBC and identify novel targeted therapies.

Keywords: breast; carcinoma; neuroendocrine.

Figure 1.

(A) Right mediolateral oblique mammogram showing an area of architectural distortion (arrow); (B) Magnification view showing in detail the area of architectural distortion along with confluent microcalcifications (arrow).

Figure 2.

Ultrasonography showing two adjacent hypoechoic nodules with irregular margins (arrow).

Figure 3.

(A) High power photomicrograph, displaying medium-sized, mildly pleomorphic tumor cells, with clear cytoplasm, medium-sized round to oval nuclei with granular chromatin and inconspicuous nucleoli. Mitoses are relatively common. (Hematoxylin & Eosin ×400); (B) Tumor cells expressing strong cytoplasmic positivity for synaptophysin (Syn ×400).

Figure 4.

(A) Almost all tumor cells expressing strong nuclear positivity for estrogen receptors (ER ×100); (B) Sentinel lymph node with metastasis, which was visible during gross description (Hematoxylin & Eosin ×100).