Small Cell Neuroendocrine Carcinoma of the Cervix: Understanding Your Pathology Report

By Jason Wasserman MD PhD FRCPC
May 16, 2026

Small cell neuroendocrine carcinoma (SCNEC) is a rare and aggressive type of cervical cancer. It develops from small cancer cells that exhibit neuroendocrine differentiation, meaning they behave like the hormone-producing cells found throughout the body. Because it is a high-grade cancer, SCNEC tends to grow quickly and spread early, often before the tumor itself is large. It accounts for less than 1% of all cervical cancers. The average age at diagnosis is approximately 48 years, but the tumor can occur in both younger and older patients. Most cases in the cervix are strongly associated with infection by high-risk types of human papillomavirus (HPV), especially HPV16 and HPV18.

This article will help you understand the findings in your pathology report, what each term means, and why it matters for your care.

What causes small cell neuroendocrine carcinoma of the cervix?

Most cases of cervical SCNEC are caused by persistent infection with high-risk types of HPV, particularly HPV16 and HPV18. HPV infects cells in the cervix and, over time, can alter their genetic material. These changes disrupt normal cell growth and survival mechanisms and can eventually lead to cancer.

Molecular studies of cervical SCNEC have identified alterations in several cancer-related pathways, including the MAPK, PI3K/AKT/mTOR, and TP53 tumor suppressor pathways. Some tumors also show loss of genetic material from the short arm of chromosome 3. These genetic changes are thought to contribute to the rapid growth and early spread that are characteristic of this cancer.

What are the symptoms?

The symptoms of cervical SCNEC are similar to those of other cervical cancers and depend on the size of the tumor and whether it has spread beyond the cervix. Common symptoms include:

Abnormal vaginal bleeding — Bleeding after intercourse, between menstrual periods, or after menopause.
Vaginal discharge — May be watery or blood-tinged.
Pelvic pain or discomfort — Often related to a larger tumor or to spread into nearby structures.
Pain during or after sexual intercourse — Caused by inflammation or tumor extension.

Because cervical SCNEC tends to spread early, some patients first seek medical attention because of symptoms caused by distant spread, such as cough or chest discomfort from involvement of the lungs, abdominal pain from involvement of the liver, or bone pain from involvement of the skeleton.

How is the diagnosis made?

The diagnosis of cervical SCNEC is made by removing tissue from the cervix and examining it under the microscope. The sample may be obtained through a biopsy taken during colposcopy, an endocervical curettage to sample tissue inside the cervical canal, a cone biopsy that removes a larger cone-shaped portion of the cervix, or a resection specimen if surgery is performed as part of treatment. After diagnosis, imaging studies are usually performed to determine how far the cancer has spread.

Because cervical SCNEC can look similar to other cancers, including HPV-associated squamous cell carcinoma and metastatic small cell carcinoma from the lung, the pathologist performs several special tests to confirm the diagnosis. Immunohistochemistry uses antibodies to detect specific proteins inside tumor cells. The tumor cells in SCNEC are typically positive for one or more neuroendocrine markers, including synaptophysin and chromogranin A, which are the most specific markers for neuroendocrine differentiation. INSM1 is a newer marker that is also highly specific and is now commonly included on the testing panel. CD56 may also be positive but is less specific. Cytokeratins are usually positive, confirming that the tumor is epithelial in origin (arising from lining cells), and the proliferation marker Ki-67 typically shows a very high percentage of dividing cells. p16 is usually strongly and diffusely positive in cervical SCNEC, reflecting its association with high-risk HPV. In situ hybridization to detect HPV genetic material may also be performed to confirm both the HPV-driven nature of the tumor and the cervical origin.

What does small cell neuroendocrine carcinoma look like under the microscope?

Under the microscope, cervical SCNEC is composed of small tumor cells with very little cytoplasm (the body of the cell) surrounding the nucleus. The nuclei are dark, a feature called hyperchromatic, and may press tightly against each other, a feature called nuclear molding. The pathologist often sees a very large number of mitotic figures (dividing tumor cells), many dying cells (apoptosis), and large areas of necrosis (dead tumor tissue). The tumor cells may grow in sheets, in nests, in cords (called trabeculae), or in small rosette-like patterns.

Tumor size and depth of invasion

Once invasive cancer is confirmed, the pathologist measures the tumor to determine its size and how deeply it has grown into the cervix. Tumor size describes the largest dimension of the cancer along the surface of the cervix and is usually reported in centimeters. Depth of invasion describes how far the tumor has grown from the surface lining into the supporting tissue (the stroma) of the cervix and is usually reported in millimeters. Depth of invasion is especially important because SCNEC tends to spread early through blood and lymphatic channels. Even small tumors that have invaded only a few millimeters can already have spread to lymph nodes or distant organs. For this reason, the risk of spread is generally higher for SCNEC than for other cervical cancers of the same size.

Tumor extension

SCNEC often extends beyond the cervix early in its course. The tumor may extend directly into nearby structures including the body of the uterus, the upper vagina, the parametrium (the fibrous tissue surrounding the cervix), the pelvic wall, the bladder, or the rectum. Tumor extension increases the pathologic stage and is associated with a higher risk of recurrence and worse outcomes. Because distant spread is also common at the time of diagnosis, imaging studies are typically used alongside the pathology report to assess for spread to organs such as the lungs, liver, or bones.

Lymphovascular invasion

Lymphovascular invasion means that tumor cells are present inside small lymphatic channels or blood vessels in the cervix. This is a very common finding in SCNEC and is one of the reasons this tumor type tends to spread early. Because lymphovascular invasion provides a pathway for the cancer to reach lymph nodes and distant organs, its presence is associated with a higher risk of lymph node involvement and distant metastasis. Its presence often influences the team’s discussion about whether to add chemotherapy and radiation therapy after surgery.

Perineural invasion

Perineural invasion means that tumor cells are growing along or around small nerves in the cervix. It is less common than lymphovascular invasion in cervical SCNEC, but when present it is associated with a higher risk of local recurrence after treatment. Its presence may influence the team’s discussion about adding radiation therapy after surgery.

Surgical margins

A margin is the cut edge of tissue removed during a surgical procedure such as a cone biopsy or hysterectomy. The pathologist examines the margins under the microscope to determine whether any cancer cells are present at the cut edges.

Negative margin — No cancer cells are present at the cut edge of the tissue. This suggests that the entire tumor was removed.
Close margin — Cancer cells are within a few millimeters of the cut edge but not reaching it. A close margin may prompt the team to consider additional treatment, depending on the rest of the pathology findings.
Positive margin — Cancer cells extend to the cut edge of the tissue. This means some cancer cells may remain in the body, which increases the risk of recurrence. Positive margins may lead the team to discuss repeat surgery, radiation therapy, or additional chemotherapy.

Because SCNEC has a high risk of recurrence even with negative margins, the margin result is interpreted alongside the other features of the tumor when planning further treatment.

Lymph nodes

Lymph nodes are small immune organs that filter fluid as it returns from the body’s tissues to the bloodstream. The cervix drains into lymph nodes in the pelvis, and from there to lymph nodes higher in the abdomen along the aorta (the para-aortic nodes). During surgery for cervical cancer, lymph nodes from these areas may be removed and examined under the microscope.

Because SCNEC is aggressive, lymph node involvement is common even when the primary tumor is small. The pathology report describes the number of lymph nodes examined, the number that contain tumor cells, the location of the involved nodes, and the size of the tumor deposit in each node:

Isolated tumor cells — Tiny clusters measuring 0.2 mm or less.
Micrometastases — Tumor deposits larger than 0.2 mm but no larger than 2 mm.
Macrometastases — Tumor deposits larger than 2 mm.

The pathology report may also note whether cancer has broken through the outer wall of a lymph node into the surrounding tissue, a finding called extranodal extension, which is associated with a higher risk of recurrence.

Biomarker and molecular testing

Biomarker testing is most relevant in advanced, recurrent, or metastatic cervical SCNEC, where the results help determine eligibility for specific systemic therapies. Not all biomarkers are tested in every case.

PD-L1

PD-L1 is a protein that some tumor cells use to suppress the immune system’s ability to recognize and destroy them. Testing for PD-L1 is performed by immunohistochemistry on a tumor sample and is reported as the Combined Positive Score (CPS), which reflects PD-L1 expression on tumor cells and on nearby immune cells. For cervical cancer, a CPS of 1 or higher is the threshold that indicates eligibility for immune checkpoint inhibitor therapy with pembrolizumab in advanced, recurrent, or metastatic disease.

Mismatch repair (MMR) testing

MMR protein testing (MLH1, PMS2, MSH2, MSH6) is sometimes performed in advanced or recurrent disease. Although MMR deficiency is uncommon in cervical SCNEC, when present, it identifies patients who may benefit from pembrolizumab, which is approved for tumors that are MMR-deficient or microsatellite instability-high (MSI-high), regardless of where the cancer started. MMR deficiency can also occasionally indicate an inherited cancer syndrome (Lynch syndrome), and referral for genetic counseling may be discussed.

Pathologic stage

Staging describes how far the cancer has spread within the cervix and beyond. Stage is the most important factor in predicting outcome, although cervical SCNEC has a higher risk of recurrence than other cervical cancers at any given stage because of its tendency to spread early. Cervical cancer is staged using two related systems: the AJCC pTNM system (currently AJCC 8th edition) and the FIGO system (currently the FIGO 2018 revision). The two systems are aligned and use the same anatomic categories, but FIGO is more commonly used by gynecologic oncologists for treatment planning.

The TNM system describes the size and extent of the tumor in the cervix (T), whether nearby lymph nodes contain cancer (N), and whether the cancer has spread to distant organs (M). The metastasis category (M) is generally determined by imaging studies rather than by examination of the surgical specimen.

Tumor stage (pT)

pT1 — Tumor confined to the cervix.
- pT1a — Invasive cancer that can be identified only under the microscope, with depth of invasion of 5 mm or less. (FIGO 2018 removed the prior 7 mm horizontal width criterion, so pT1a is now defined by depth alone.)
  - pT1a1 — Depth of invasion 3 mm or less.
  - pT1a2 — Depth of invasion greater than 3 mm but no more than 5 mm.
- pT1b — Invasive cancer with depth of invasion greater than 5 mm, still confined to the cervix.
  - pT1b1 — Tumor 2 cm or less in greatest dimension.
  - pT1b2 — Tumor greater than 2 cm but no more than 4 cm.
  - pT1b3 — Tumor greater than 4 cm.
pT2 — Tumor extends beyond the cervix but has not reached the pelvic wall or the lower third of the vagina.
- pT2a — Tumor involves the upper two-thirds of the vagina but not the parametrium. Subdivided into pT2a1 (4 cm or less) and pT2a2 (greater than 4 cm).
- pT2b — Tumor has invaded the parametrium.
pT3 — Tumor involves the lower third of the vagina, reaches the pelvic wall, or blocks a ureter (which can damage the kidney).
- pT3a — Tumor involves the lower third of the vagina without extension to the pelvic wall.
- pT3b — Tumor extends to the pelvic wall, blocks a ureter, or both.
pT4 — Tumor has grown into the lining of the bladder or rectum, or has extended beyond the pelvis.

Nodal stage (pN)

pNX — Regional lymph nodes were not examined.
pN0 — No cancer found in the examined regional lymph nodes.
pN0(i+) — Only isolated tumor cells (clusters 0.2 mm or smaller) are present in regional lymph nodes.
pN1 — Larger tumor deposits are present in regional lymph nodes.
- pN1a — Metastasis to pelvic lymph nodes only.
- pN1b — Metastasis to para-aortic lymph nodes, with or without pelvic lymph node involvement.

Metastatic stage (pM)

The metastasis category is determined by imaging studies and clinical evaluation rather than by examination of the surgical specimen. pM0 means no distant spread has been identified. pM1 means cancer has spread to distant organs such as the lungs, liver, or bones.

FIGO stage

The FIGO stage is reported alongside the TNM stage. It reflects the combined pathologic and imaging findings and is the system most commonly used to guide treatment planning:

Stage I — Cancer confined to the cervix. Subdivided into IA1, IA2, IB1, IB2, and IB3 using the same depth and size cut-offs as the AJCC pT1 categories above.
Stage II — Cancer has spread beyond the cervix but has not reached the pelvic wall or the lower third of the vagina. Subdivided into IIA1 (upper vagina, 4 cm or less), IIA2 (upper vagina, greater than 4 cm), and IIB (parametrial invasion).
Stage III — More extensive spread.
- Stage IIIA — Cancer involves the lower third of the vagina.
- Stage IIIB — Cancer reaches the pelvic wall or blocks a ureter.
- Stage IIIC1 — Cancer is present in pelvic lymph nodes (regardless of tumor size).
- Stage IIIC2 — Cancer is present in para-aortic lymph nodes (regardless of tumor size).
Stage IV — Cancer has spread to nearby organs or distant sites.
- Stage IVA — Cancer invades the lining of the bladder or rectum.
- Stage IVB — Cancer has spread to distant organs such as the lungs, liver, or bones.

What is the prognosis?

The prognosis for cervical SCNEC is generally less favorable than for other types of cervical cancer. Several factors contribute to this. The tumor grows quickly, often spreads to lymph nodes and distant organs before it is diagnosed, and is more likely to recur after treatment than other cervical cancers. Even patients with early-stage disease have a meaningfully higher risk of recurrence than patients with squamous cell carcinoma or adenocarcinoma of the cervix at the same stage. Survival rates published in the literature are lower across all stages. While five-year survival for early-stage cervical squamous cell carcinoma may exceed 90%, early-stage cervical SCNEC has a substantially lower five-year survival rate, and patients with advanced disease often have survival measured in months rather than years.

Several features of the pathology report influence the chance of recurrence:

Stage at diagnosis — The most important prognostic factor. Earlier stages have better outcomes, but outcomes are less favorable than for other cervical cancers at any given stage.
Lymph node involvement — Common in cervical SCNEC and strongly associated with reduced survival.
Lymphovascular invasion — Very common in cervical SCNEC and associated with a higher risk of distant spread.
Tumor size and depth of invasion — Larger and deeper tumors carry a higher risk of recurrence and worse outcomes.
Perineural invasion — When present, is associated with a higher risk of local recurrence.
Surgical margin status — Negative margins are associated with a lower risk of local recurrence; positive margins increase the chance of residual disease.
Response to initial chemotherapy and radiation — Many patients respond initially to treatment, but recurrences are common and often occur within the first two years after diagnosis.

What happens after this diagnosis?

Once cervical SCNEC is diagnosed, the gynecologic oncology, medical oncology, and radiation oncology teams work together to discuss treatment options with the patient. Because cervical SCNEC behaves more aggressively than other cervical cancers, treatment usually combines several modalities, even for patients with apparently early-stage disease. Fertility-preserving surgery is rarely an option for cervical SCNEC because of the high risk of early spread.

Options the team may consider include:

Radical hysterectomy with pelvic lymph node assessment — For early-stage disease, surgery may be combined with sentinel lymph node biopsy or pelvic lymph node dissection. The pathology findings from this specimen guide whether additional treatment is needed afterward.
Combined chemotherapy and radiation — For locally advanced disease, the standard approach is chemotherapy combined with radiation. Chemotherapy for SCNEC is typically platinum-based and resembles the regimen used for small cell carcinoma of the lung (such as cisplatin or carboplatin combined with etoposide).
Adjuvant chemotherapy after surgery — Even patients with early-stage disease often receive systemic chemotherapy after surgery because the risk of distant recurrence is high.
Systemic therapy for advanced or recurrent disease — For stage IVB or recurrent disease, the medical oncology team discusses systemic options. Eligibility for immunotherapy (pembrolizumab) depends on the PD-L1 result, MMR/MSI status, and the clinical scenario. Newer therapies under investigation for small cell carcinomas, including DLL3-targeted agents and other novel approaches, may be discussed.
Clinical trials — Because cervical SCNEC is rare and standard treatments have limited durability, enrollment in clinical trials of new combinations and novel agents is often discussed.

Close follow-up after treatment is essential. Because most recurrences occur within the first two to three years after diagnosis, surveillance is typically more frequent during this period. Follow-up usually includes regular physical and pelvic examinations, imaging at intervals determined by the original stage and pathology findings, and ongoing communication with the multidisciplinary care team.

Questions to ask your doctor

What is the stage of my cancer using both the TNM and FIGO systems?
How large is the tumor, and how deeply has it grown into the cervix?
Were neuroendocrine markers such as synaptophysin, chromogranin, and INSM1 confirmed on my biopsy?
Was lymphovascular invasion or perineural invasion present?
How many lymph nodes were examined, and were any involved?
Were the surgical margins negative, close, or positive?
Was PD-L1 testing performed, and what does the result mean for my treatment options?
Was MMR or MSI testing performed, and what did it show?
What treatment options would you discuss with me based on my pathology findings?
Will my treatment include surgery, chemotherapy, radiation therapy, or some combination?
Are there clinical trials available that might be appropriate for me?
What is my chance of the cancer coming back, and what symptoms should I watch for?
What follow-up tests and appointments will I need, and how often?
How will my care be coordinated between my gynecologic oncology, medical oncology, and radiation oncology teams?