Primary Small Cell Neuroendocrine Carcinoma of the Vagina: A Clinicopathologic Study

Primary small cell neuroendocrine carcinoma of the female genital tract is a rare entity that has been reported to originate in the cervix,1,2 endometrium,3–6 ovary,7 vagina,8–14 and vulva15 in decreasing frequency. To our knowledge, 22 prior cases of primary vaginal small cell neuroendocrine carcinoma have been reported in the English literature. The histologic, immunohistochemical, and ultrastructural profiles are similar to small cell carcinoma originating in other primary sites. Primary small cell neuroendocrine carcinoma of the vagina has an aggressive behavior and a very poor prognosis, even with the current therapeutic modalities. We report the clinicopathologic study of 3 cases of primary vaginal small cell neuroendocrine carcinoma.

A 74-year-old white woman presented with vaginal bleeding and, at the time of evaluation in February 1997, had a pelvic mass. Ultrasound findings were significant for an 8.5-cm pelvic mass. A computed tomographic scan showed a large pelvic mass, 7.5 × 5 cm, contracting the small bowel and sigmoid colon; significant pelvic and periaortic lymphadenopathy; and a right pleural effusion. A bone scan was negative.

The patient had no significant medical history. Her surgical history was significant for a transvaginal hysterectomy and bilateral salphingoophorectomy in 1995 for postmenopausal bleeding. Pathology at the time of hysterectomy was negative for any malignancy. A biopsy of the vaginal mass was consistent with small cell neuroendocrine carcinoma. The disease was designated AJCC (American Joint Committee on Cancer) pathologic stage IV (pT3 N1 M1). She was offered palliative chemotherapy and radiation therapy. The patient was treated with one cycle of CDDP (cis-diamminedichlorplatinum) on day 1 of the cycle and with etoposide on days 1 through 3 of the cycle, along with pelvic radiation. She was evaluated 3 days later and was noted to have a 20% reduction in the pelvic mass. A week later, the patient developed a skin rash, nausea, and diarrhea and was referred for hospice care. She died 4 months after her initial diagnosis.

A 55-year-old Latin American woman presented complaining of vaginal spotting in August 1997. A physical examination showed a 7 × 3 × 3-cm vaginal mass at the introitus in close proximity to the Bartholin gland on the right side. A biopsy was consistent with an undifferentiated small cell malignant neoplasm. A computed tomographic scan confirmed the presence of a vaginal mass arising from the right side of the vagina and a 2-cm lymph node in the right inguinal area. A bone scan and chest x-ray were negative. The patient had no significant medical or surgical history. She had one abnormal Papanicolaou test (atypical glandular cells of undetermined significance [AGUS]) in 1992 and failed to follow up for further evaluation. Her social history was significant for smoking, alcohol, and drug abuse. Her human immunodeficiency virus status was negative. She underwent a radical vulvectomy, partial vaginectomy, and bilateral inguinal lymph node dissection. Two of 8 ipsilateral lymph nodes were positive. The disease was designated AJCC pathologic stage III (pT2 N1 M0). The patient was offered adjuvant chemoradiation therapy, which she declined. She returned in December 1997 complaining of vulvar swelling and a purulent discharge. On evaluation, she was also found to have supraclavicular lymphadenopathy. A bone scan showed increased uptake in several areas of the right humerus. She received one cycle of CDDP and etoposide. She became severely neutropenic, developed line sepsis, and died several days later from septic shock.

A 38-year-old black woman was admitted through the emergency department with severe rectal pain in April 2003. A physical examination showed a 10 × 8 × 8-cm rectovaginal mass with areas of ulceration from both the vaginal and rectal sides. The mass was in close proximity to the introitus without any cervical involvement. A biopsy showed a poorly differentiated carcinoma favoring small cell carcinoma. A computed tomographic scan and bone scan were negative for metastatic disease. The disease was designated stage IV (T4 NX M0). She was offered combined chemoradiation therapy and received one cycle of CDDP on day 1 of the cycle and etoposide on days 1 through 3 of the cycle; she next received 3 additional cycles of CDDP alone concurrent with external beam radiation therapy, which was followed by brachytherapy (vaginal cylinder). She completed her treatment in May 2003 with a good response.

The database of the Department of Pathology of the University of Texas Medical Branch at Galveston was searched for the period 1990–2003 for the diagnosis of primary small cell neuroendocrine carcinoma of the vagina. Three cases were identified, and the medical charts were reviewed. Clinical data were available for each of the 3 patients, including age, race, medical history, surgical history, stage of the disease, clinical management, and follow-up information.

The specimen was fixed in a 10% neutral-buffered formalin solution and prosected as a routine surgical pathology specimen. The whole specimen (or representative sections) was embedded in paraffin, processed in the usual manner, and stained with hematoxylin-eosin.

Immunohistochemical staining was performed on formalin-fixed, paraffin-embedded 4-μm tissue sections with the avidin-biotin immunoperoxidase complex method16 (LSAB2 system, Dako Corporation, Carpinteria, Calif) with diaminobenzidine as the chromogen and hematoxylin as the nuclear counterstain. Information about the antibodies used is summarized in Table 1. For the antibodies that were used, the antigens from the tissue sections were retrieved prior to immunohistochemistry by incubating them in a Black and Decker Vegetable Steamer for 20 minutes in Target Retrieval Solution (Dako) preheated to 99°C. The negative control was performed by substituting the primary antibody with nonimmune mouse or rabbit serum. The following tissues were used for the positive controls of immunostains: normal pancreatic tissue for chromagranin A and synaptophysin, skin for cytokeratins, tonsilar tissue for CD45, and thyroid tissue for thyroid transcription factor 1 (TTF-1). Positive and negative controls were run simultaneously and stained appropriately.

For electron microscopy, small blocks of fresh tumor were fixed in 2.5% glutaraldehyde and embedded in Spurr resin. Thin sections of the tumor were stained with uranyl acetate and lead citrate.

The histologic features of all 3 neoplasms were similar. Hematoxylin-eosin–stained sections showed nests and cords of closely packed small cells with scanty cytoplasm and indistinct cell borders (Figure 1). The nuclei were hyperchromatic with fine stippled chromatin and inconspicuous nucleoli (Figure 1). Mitotic figures were brisk, and areas of necrosis were frequently observed. Nuclear encrustation was present in case 2 (Figure 1).

Several immunohistochemical stains were used on all 3 cases, which included TTF-1, cytokeratin, chromogranin A, and synaptophysin (Table 2). Case 2 showed strong diffuse nuclear staining for TTF-1 (Figure 2, A), while cases 1 and 3 were negative. The tumor cells of all 3 cases showed streaky, focal staining for low-molecular-weight cytokeratins (Figure 2, B). All tumor cells showed diffuse positivity for chromogranin A (Figure 2, C) and synaptophysin (Figure 2, D). The tumor cells in all cases were also subjected to CD45 staining and were all negative.

Ultrastructurally, the tumor consisted of tightly packed small and undifferentiated cells with a high nuclear–cytoplasmic ratio. Occasional cell junctions and rare desmosomes were observed joining the tumor cells. The nuclei were round or ovoid with evenly distributed clumped heterochromatin. The cytoplasm was scanty and contained a few mitochondria and moderate amounts of glycogen. Occasional membrane-bounded dense-core neurosecretory granules with a diameter of 150 nm were present in some cells (Figure 3).

Primary small cell neuroendocrine carcinoma of the vagina, first reported in 1984 by Scully et al,17 is a rare neoplasm with only 22 cases8–14,17–24 reported in the English literature to date. The histologic findings are those of typical and classic small cell carcinoma, consisting of tightly packed, small, round, oval and spindle cells with scant cytoplasm, ill-defined cell borders, fine granular nuclear chromatin and absent or inconspicuous nucleoli, and nuclear molding with no definitive differentiation into the epithelial structure that can be observed with light microscopy. Immunohistochemical staining for cytokeratin is often required to confirm the epithelial origin and exclude other small blue cell tumors, such as lymphoma and sarcoma. The immunohistochemical staining patterns for the neuroendocrine features of the vaginal small cell carcinoma have been studied in only a few of the previously reported 22 cases (ie, 6 cases for neuron-specific enolase,9,11,13,18,19 4 cases for synaptophysin,8,9,13,19 and 5 cases for chromogranin A8,11,13,18,19). Combined with the present study, neuron-specific enolase and synaptophysin were performed in 7 cases, and all showed strong positivity. The tumor cells of 8 cases were subjected to the chromogranin A stain; 6 were positive,13,18,19 1 was weakly positive,8 and 1 was negative.9 The neuroendocrine nature of the tumors was investigated in 11 cases by electron microscopy9,12,18–22; all showed scattered dense-core neurosecretory granules. The expression pattern of TTF-1 was not reported previously in small cell neuroendocrine carcinoma of the vagina. In the present study, TTF-1 immunostaining was performed in all 3 cases. Two cases were negative, and 1 case was positive. The positive staining for TTF-1 in case 2 initiated diligent clinical and radiologic evaluations of the patient's pulmonary and thyroid status. These evaluations revealed no evidence of any neoplasm at those sites. Human TTF-1 is a 38-kd homeodomain transcription factor of the NKx2 family that is almost exclusively expressed in the normal thyroid and lung as well as in carcinomas derived from these organs.25 TTF-1 is a sensitive but not absolutely specific marker for small cell lung carcinoma. It has been reported to be expressed in nonpulmonary small cell carcinomas that have originated in the gastrointestinal tract, urinary bladder, and uterine cervix.25 To our knowledge, this is the first report of the expression of the TTF-1 in small cell carcinoma of the vagina, indicating that TTF-1 is not a specific marker for small cell lung carcinoma and should not be used to distinguish primary from metastatic small cell carcinoma in extrapulmonary sites.26 Complete clinical evaluation is essential to establish the origin of the tumor and rule out metastasis.

Small cell carcinoma of the vagina must be distinguished from the small cell variant of squamous cell carcinoma and basaloid carcinoma.27,28 The small cell variant of squamous cell carcinoma is a poorly differentiated carcinoma with small tumor cells that retain morphologic characteristics of a non–small cell carcinoma and show focal squamous differentiation. This variant of squamous cell carcinoma must be distinguished from combined small cell carcinoma in which there is a mixture of squamous cell carcinoma and true small cell carcinoma. The small cell variant of squamous cell carcinoma lacks the characteristic nuclear features of small cell carcinoma. The tumor cells show nuclei with coarse or vesicular chromatin, prominent nucleoli, and more distinct cytoplasmic cell borders. Focal intercellular bridges may be seen. The basaloid variant of squamous cell carcinoma and basaloid carcinoma is composed of tumor nests with prominent peripheral palisading primarily in relatively small monomorphic cuboidal-to-fusiform cells with moderately hyperchromatic nuclei, fine granular chromatin, absent or only focal nucleoli, scant cytoplasm, and a high mitotic rate. In basaloid carcinoma, neither intercellular bridges nor individual cell keratinization is present. However, these tumors commonly contain a comedo necrosis. Rosettes are seen in approximately one third of the cases.29 Immunohistochemical stains for neuroendocrine markers are usually negative, and no neurosecretory granules are observed with electron microscopy. Immunohistochemical staining for high-molecular-weight keratin (34Eβ12) is commonly positive in the basaloid variant of squamous cell carcinoma and basaloid carcinoma and negative in the small cell neuroendocrine tumor.30,31 Accurate diagnosis of small cell neuroendocrine carcinoma and its distinction from non–small cell carcinoma will determine the patient's management and prognosis.

The diagnosis of primary small cell carcinoma of the vagina is dependent on being able to exclude a direct extension of the tumor from the cervix and metastasis from the lung and other extrapulmonary sites. Our review of the literature regarding small cell carcinoma of the vagina is summarized in Table 3. All 3 of the patients of our study had undergone extensive clinical staging evaluation, and no cervical or pulmonary lesions were identified. Of the 22 patients reported in the English literature to date, clinical and pathologic information is available for 20. The mean age of our patients was 56 years (range, 38–74), which is similar to the mean age of 59 years in all 20 cases reported to date (range, 32–78). Four patients presented with stage I, 8 patients with stage II, 5 with stage III, and 3 with stage IV, with most patients dying of the disease within 2 years. The 3 patients of our study either presented initially with massive metastatic disease (case 1, stage IV) or extensive local disease (case 3, stage IV) or developed disseminated disease very rapidly (case 2, stage III). Except for the newly diagnosed patient, 2 patients died within 4 months of the initial diagnosis (cases 1 and 2).

No consensus has been reached regarding the optimal therapy, since the disease is so rare, and the current therapies have usually resulted in poor outcomes. The initial treatment options are usually based on the patient's clinical stage. For lesions that are small without evidence of metastasis, surgical resection with a partial or total vaginovulvectomy with bilateral inguinal and pelvic lymphadenectomy may be indicated, followed by chemoradiation therapy. Given the limited clinical experience with this rare tumor, the therapeutic modalities with these patients should be explored.