Neuroendocrine small cell carcinoma of the cervix: A case report

Abstract

Merkel cell polyomavirus (MCPyV) has been found in patients with Merkel cell carcinoma and respiratory tract infections. Merkel cell carcinoma is a primary aggressive neuroendocrine carcinoma of the skin. It has been demonstrated that MCPyV can be transmitted during sexual activity and may be present in the oral and anogenital mucosa. The aim of the present study was to evaluate whether MCPyV coexisted with HPV in three cases of neuroendocrine small cell carcinoma of the cervix using PCR and immunohistochemical analysis Three cases of NSC of the cervix were identified in the pathology archives of Parma University (Italy). Of these, two cases were associated with an adenocarcinomatous component. A set of general primers from the L1 region (forward, L1C1 and reverse, L1C2 or L1C2M) was PCR amplified to detect the broad-spectrum DNA of genital HPV. The presence of MCPyV was investigated via immunohistochemistry using a mouse monoclonal antibody against the MCPyV LT antigen and through PCR analysis to separate viral DNA. HPV DNA was present in all three neuroendocrine carcinomas and in the adenocarcinoma component of the two mixed cases. None of the cases were immunoreactive to CM2B4 and did not contain viral DNA in either their neuroendocrine or adenocarcinomatous component. Whilst it is difficult to draw definitive conclusions from such a small sample size, these data suggested that MCPyV does not coexist with HPV in the cervix. However, in the present study, the absence of detectable MCPyV may have been due to the presence of a genotype that was not detected by the primers used in the PCR analysis or by the antibody used for the immunohistochemical study. MCPyV microRNA may also have been present, inhibiting LT expression. Additional studies with larger cohorts and more advanced molecular biology techniques are required to confirm the hypothesis of the current study.

Keywords: human papilloma virus; immunohistochemistry; merkel cell polyomavirus; neuroendocrine small cell carcinoma; polymerase chain reaction.

Figure 1

Histological section of an Merkel cell carcinoma used as positive control for PCR analysis and immunohistochemical study. (A) Under microscopic examination, the neoplasm exhibited a nodular pattern that was composed of small blue neoplastic cells (magnification, x100). (B) The neoplastic cells exhibited nuclear positivity for the CM2B4 antibody (magnification, x200).

Figure 2

Case 1. Under microscopic examination, the neoplasm was composed of (A) a well-differentiated cervical adenocarcinomatous component (magnification, x100) and (B) a neuroendocrine component characterized by small cells with focal necrosis (asterisk), round or ovoid nuclei with finely granular chromatin, evident nucleoli and numerous mitoses (arrows) (magnification, x200). (C) The neuroendocrine component exhibited intense membrane immunoreactivity for synaptophysin (magnification, x200). (D) Granular, dot-like perinuclear citoplasmic positivity was demonstrated for chromogranin (magnification, x200) and (E) diffuse membrane immunoreactivity for CAM 5.2 was exhibited (magnification, x200).

Figure 3

Molecular analysis of the three cases. (A) Results of qualitative PCR amplification for HPV DNA using a set of general primers for the L1 region (18). Strong positivity was demonstrated in all three neoplasms, both in the NE and in the AC component. (B) Results of qualitative PCR amplification for MCPyV DNA, using a set of specific primers (19). Negativity was demonstrated in all neoplasms. HPV, human papilloma virus; NE, neuroendocrine; AC, adenocarcinomatous component; MCCPyV, merkel cell poliomavirus virus; MW, molecular weight standard; POS, positive control; H₂O, sterile water used as the negative control.

Figure 4

Case 2. Following histologic examination, the lesion exhibited (A) nests and cords of small blue neoplastic cells (magnification, x200), with (B) round or ovoid nuclei, finely granular chromatin, small nucleoli and a high mitotic rate (arrows) (magnification, x400). (C) Neoplastic cells exhibited membrane immunoreactivity for synaptophysin (magnification, x400). (D) CD56 (magnification, x100) and (E) CAM5.2 (magnification, x200) staining confirmed the lesion was neuroendocrine in nature. Immunohistochemical analysis revealed (F) diffuse cytoplasmic and nuclear over-expression of p16 (magnification, x100) and (G) negativity for CM2B4 antibody (magnification, x200), which was indicative of merkel cell poliomavirus virus negativity.

Figure 5

Case 3. Histologically, the neoplasm consisted of two components. (A) The neuroendocrine component was characterized by cords and trabecula of oval to spindle-shaped cells, with scant cytoplasm and numerous mitoses (arrows) and individual cell necrosis with karyorrhexis and karyolysis (asterisk) (magnification, x200). (B) The second component exhibited well-differentiated cervical adenocarcinoma (magnification, x200). (C) Using immunohistochemistry, the neuroendocrine component exhibited granular, dot-like perinuclear citoplasmic positivity for chromogranin A (magnification, x200). (D) Intense membrane immunoreactivity for synaptophysin was demonstrated (magnification, x100). (E) Membrane and cytoplasmic positivity for CAM5.2 was also revealed (magnification, x200).

Figure 6

Case 3. Diffuse and marked immunohistochemical positivity for p16 protein were observed in both the (A) neuroendocrine (magnification, x100) and (B) adenocarcinomatous components (magnification, x100). (C) Negativity for merkel cell poliomavirus virus was observed in both the neuroendocrine (magnification, x200) and (D) adenocarcinomatous components (magnification, x200).