Malignancies in Clitoris: A Review of Literature on Etiology, Diagnosis, Pathology and Treatment Strategies

Case report: Clitoral adenocarcinoma in a mixed-breed female dog

A 9-year-old, spayed female, mixed-breed dog was initially presented for evaluation of chronic dermatitis on the nasal planum, where a clitoral mass was discovered as an incidental finding during the exam. No further investigation of the clitoral mass was undertaken due to other significant dermal lesions and the lack of clinical significance of the mass at the time. However, ~1 month later, the dog was presented to the Emergency Service for bleeding from the vulva. The clitoral mass was found to have prolapsed; the mass was manually reduced back into a position within the vulvar folds and maintained with a purse-string suture. The dog was referred to the Theriogenology Service for further investigation and removal. On follow-up evaluation, the mass was noted to be multi-lobulated, ulcerated, cystic, and involving the clitoris but not the urethra. The urethra was easily catheterized, and no urinary abnormalities were found. No evidence of lymph node metastasis or hypercalcemia was noted prior to surgery. Ultrasonographic evaluation of the anal sacs was normal. The mass was removed, and histopathologic evaluation revealed a primary clitoral adenocarcinoma. On recheck evaluation, after 1 month, no evidence of metastasis or local recurrence was observed. Clitoral adenocarcinoma is a rarely reported neoplasm of the canine genital tract that shares many clinical, histopathological, and immunohistochemical features with canine apocrine gland anal sac adenocarcinoma. This case adds to the available knowledge on the condition, specifically regarding the frequency of complications such as hypercalcemia and metastasis, as previous reports suggest that these are present at least 50% of the time.

Canine Clitoral Carcinoma: A Clinical, Cytologic, Histopathologic, Immunohistochemical, and Ultrastructural Study

Vaginal and vulvar tumors are uncommon in dogs. Knowledge of canine primary clitoral neoplasia is restricted to a few case reports, and only carcinomas have been reported. Cytologic and histologic features reported in the literature seem to overlap with those of canine apocrine gland anal sac adenocarcinoma (AGASA). Clinical features also recall those of canine AGASA, such as locoregional metastases and hypercalcemia of malignancy (HM). In this study, 6 cases of primary canine clitoral carcinomas (CCCs), with and without HM, were investigated by means of cytology, histopathology, electron microscopy, and immunohistochemistry for neuroendocrine markers including chromogranin A (CGA), synaptophysin (SYN), neuron-specific enolase (NSE), and S-100. In all 6 tumors, cytologic findings were consistent with malignant epithelial neoplasia of apocrine gland origin. The tumors examined were classified into 3 different histological patterns representing different degrees of differentiation: tubular, solid, and rosette type. Both CGA and SYN were mildly expressed in 2 of 6 tumors, while NSE was consistently expressed in all 6 cases. None of the tumors were S-100 positive. Transmission electron microscopy revealed electron-dense cytoplasmic granules compatible with neuroendocrine granules in all 6 cases. CCCs presented clinicopathologic features resembling AGASAs with neuroendocrine characteristics, and 2 of 6 neoplasms were considered as carcinomas with neuroendocrine differentiation and were positive for 3 neuroendocrine markers. CCCs can often present with HM, and long-term outcome is likely poor. Our study concludes that CCC seems to be a rare tumor, but it might be underestimated because of the overlapping features with AGASA. Further studies should aim to define the true incidence of this disease.