How Multimodality Imaging Helps Diagnose Primary Small Cell Carcinoma of the Breast

Breast cancer is the most common cancer in women worldwide, but some rare subtypes—like primary small cell carcinoma of the breast (PSCCB)—can be tricky to diagnose. PSCCB accounts for less than 1% of all breast cancers and combines aggressive small cell features with neuroendocrine markers, making early detection critical for survival. A 2019 case study from researchers at The First Hospital of Lanzhou University in China highlights how multimodality imaging (combining mammography, ultrasound, MRI, and PET-CT) plays a key role in identifying this rare tumor—and guiding life-saving treatment.

The Case: A 51-Year-Old Woman with a Palpable Breast Mass

The study centers on a 51-year-old woman who visited her doctor after finding a lump in her left breast. She had no redness, nipple discharge, or other symptoms—common for PSCCB, which often presents as a “silent” palpable mass.

Imaging revealed critical clues:

Mammography: A round, well-defined mass without calcifications in the left breast’s lower outer area.
Ultrasound: A heterogeneous, hypoechoic (darker) lesion with blood flow around its edges—a sign of abnormal tissue growth.
MRI: A 2.6cm x 2.5cm mass that appeared dark on T1-weighted images (typical for dense tissue) and very bright on fat-suppressed T2-weighted images (indicating fluid or necrosis). The apparent diffusion coefficient (ADC) value—an MRI measure of water movement in tissues—was low (0.893 x 10⁻³ mm²/s), a red flag for cancer (benign lesions usually have higher ADC values). Contrast-enhanced MRI showed “rim enhancement” (bright edges around the mass) and a “plateau” pattern (steady contrast uptake over time)—features linked to aggressive tumors.
PET-CT: Fluorodeoxyglucose (FDG) uptake in the breast mass only—ruling out metastases from other small cell cancers (like lung cancer), which is essential for diagnosing PSCCB as primary.

A ultrasound-guided biopsy confirmed small cell carcinoma, and surgery (breast conservation + sentinel lymph node biopsy) followed. Post-op pathology revealed small, round cancer cells with high proliferation (Ki-67 >90%) and positive neuroendocrine markers (synaptophysin, chromogranin A)—hallmarks of PSCCB. The tumor was also “triple negative” (ER/PR/HER2 negative), meaning hormone or targeted therapies wouldn’t work. The patient received four cycles of chemotherapy (etoposide + cisplatin), a standard regimen for small cell cancers.

What Is Primary Small Cell Carcinoma of the Breast?

PSCCB is a rare invasive breast cancer with neuroendocrine features—meaning the cancer cells resemble cells that produce hormones or neurotransmitters. Researchers believe it starts in multipotent stem cells that develop neuroendocrine traits. Most cases occur in women around age 53 (range: 28–81), and like this patient, many present with a painless lump.

Pathologically, PSCCB mixes two components: small cell carcinoma (SCC) (aggressive, fast-growing) and ductal carcinoma in situ (DCIS) (non-invasive). The ratio of these components changes the imaging appearance:

If DCIS is dominant: Imaging looks like typical DCIS (e.g., microcalcifications).
If SCC is dominant: Imaging shows aggressive features (low ADC, rim enhancement, plateau/washout patterns)—similar to triple-negative breast cancer (TNBC), as seen in this case.

Why Multimodality Imaging Matters

While pathologic biopsy is the “gold standard” for diagnosing PSCCB, imaging solves two critical problems:

Ruling out metastases: Small cell cancers often spread from other organs (e.g., lung). PET-CT confirmed this patient’s cancer was primary (no other tumors).
Guiding treatment: Imaging reveals how the tumor is growing (e.g., rim enhancement suggests central necrosis) and whether it has spread—key for choosing surgery, chemo, or radiation.

Imaging also helps differentiate PSCCB from look-alike tumors:

Mucinous carcinoma: Benign-looking with “colloid” (mucus-rich) stroma. MRI shows persistent enhancement and very high ADC values (higher than most benign lesions).
Medullary carcinoma: Well-defined, poorly differentiated cells with lymphoid infiltration. Central necrosis is common, but pathology (not imaging) confirms the difference.

Treatment and Prognosis

PSCCB is rare, so no formal treatment guidelines exist. Doctors use a mix of breast cancer and small cell lung cancer protocols:

Surgery: Removes the tumor and checks lymph nodes (as in this case).
Chemotherapy: Etoposide + cisplatin is standard for small cell cancers.
Radiation: May be added if the tumor is large or lymph nodes are involved.

A 2011 study of 53 PSCCB cases found ~75% are ER/PR negative (like this patient), so hormone therapy isn’t useful. HER2 overexpression is rare, so targeted drugs (e.g., trastuzumab) don’t help. The 18.9% mortality rate in that study (follow-up: 3–60 months) underscores why early detection—via imaging—is so important.

Key Takeaways

For a rare cancer like PSCCB, multimodality imaging is more than just a “tool”—it’s a bridge between a patient’s symptoms and life-saving care. By combining mammography, ultrasound, MRI, and PET-CT, doctors can:

Identify aggressive features (low ADC, rim enhancement) that signal PSCCB.
Rule out metastases to confirm the cancer is primary.
Plan surgery and chemo to target the tumor’s unique biology.

This case from Lanzhou University reminds us that even rare cancers can be diagnosed early—if we use the right tools.

The authors obtained full patient consent for publishing her clinical information and images. The study was funded by the Lanzhou Talent Innovation and Entrepreneurship Project Foundation (No. 2017-RC-76). The authors declare no conflicts of interest.

References

Mirza IA, Shahab N. Small cell carcinoma of the breast. Semin Oncol. 2007;34:64–66. doi: doi.org/10.1053/j.seminoncol.2006.10.029
Kanat O, Kilickap S, Korkmaz T, Ustaalioglu Oven BB, Canhoroz M, Cubukcu E, et al. Primary small cell carcinoma of the breast: report of seven cases and review of the literature. Tumori. 2011;97:473–478. doi: doi.org/10.1700/950.10400
Amano M, Ogura K, Ozaki Y, Tamai M, Kitabatake T, Fujisawa M, et al. Two cases of primary small cell carcinoma of the breast showing non-mass-like pattern on diagnostic imaging and histopathology. Breast Cancer. 2015;22:437–441. doi: doi.org/10.1007/s12282-012-0397-3
Mariscal A, Balliu E, Díaz R, Casas JD, Gallart AM. Primary oat cell carcinoma of the breast: imaging features. AJR Am J Roentgenol. 2004;183:1169–1171. doi: doi.org/10.2214/ajr.183.4.1831169

Original study by Zhuan-Zhuan Guo, Wen Feng, Hai-Feng Liu, Xing-Ru Lu, and Jun-Qiang Lei from the Department of Radiology, The First Hospital of Lanzhou University, and The First Clinical Medical College of Lanzhou University, Lanzhou, Gansu, China. Published in Chinese Medical Journal 2019;132(10):1250–1252. doi: doi.org/10.1097/CM9.0000000000000226

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