Primary high-grade neuroendocrine carcinoma with positive steroid hormone receptors arising in the inguinal skin: A case report of An exceedingly rare entity

Abstract

Introduction: Neuroendocrine tumors usually arise from the gastrointestinal and pulmonary tracts and rarely from the skin. We report a unique case of high-grade neuroendocrine carcinoma with positive steroid hormone receptors in the primary skin of the groin.

Case presentation: A 79-year-old female presented with a lump in her left inguinal region for 15 years that grew gradually. The tumor cells were arranged in sheets, solid nests, and bands within a rich network of thin-walled capillaries. Mucin was abundant in the stroma, and the tumor cells exhibited high-grade lesions, significant necrosis, and frequent mitosis, with small scattered foci of low-grade components. Immunohistochemistry revealed that the tumor cells diffusely and strongly expressed cytokeratin, synaptophysin, chromogranin A, GATA3, CAM5.2, and estrogen and progesterone receptors; partially expressed AR and GCDFP15.

Diagnosis: Based on pathological morphology, and immunohistochemical staining, it was confirmed as Primary high-grade neuroendocrine carcinoma with positive steroid hormone receptors arising in the inguinal skin. The patient underwent resection of the inguinal tumor and left inguinal lymph node dissection.

Interventions: The patient has been followed up for 16 months and has not undergone further examinations or received additional treatment. There is no evidence of tumor recurrence at the site of the original surgical resection, and the patient general condition is satisfactory.

Conclusions: The morphology of this tumor is unique and previously unreported, further expanding the possible pathogenesis and histological morphologies of this tumor type.

Figure 1.

Neuroendocrine carcinoma. The tumor appears gray-white to gray-brown and shows cystic changes.

Figure 2.

Neuroendocrine carcinoma images. Low-magnification microscope image showing that the tumor is located in the dermis and subcutaneous tissue, and the tumor cells are arranged in sheet-, solid nest-, and ribbon-like structures (A × 20). Low-magnification microscope image showing that the tumor has sieve-like and pseudoglandular structures formed by cells within the nests, with significant visible necrosis (B × 100). Cytologically, the tumor shows high-grade features with abundant cytoplasm; amphophilic, large round or oval nuclei with dispersed chromatin; prominent nucleoli; and evidence of necrosis and calcification (C × 400). The nucleoli are prominent, and mitosis is easily observed, as indicated by the arrow (D × 400). An area of low-grade neuroendocrine carcinoma, with cells having eosinophilic cytoplasm and small, uniform nuclei (E × 400). Tumor cell clusters or nests float in the mucinous stroma, resembling the pattern of breast mucinous carcinoma type B (F × 200).

Figure 3.

Immunohistochemistry showing diffuse positive expression of chromogranin A (A × 200). Immunohistochemistry showing almost 100% expression of ER in tumor cells (B × 200). Immunohistochemistry showing diffuse positive expression of GATA-3 (C × 200). Immunohistochemistry showing negative expression of CK7 (D × 200).