Primary renal carcinoid is extremely rare, well-differentiated neuroendocrine tumor of unknown etiology. The origin of this tumor is still unclear as neuroendocrine cells are not normally present in the renal parenchyma. There have been 50 cases reported in the literature, with a strong partnership with the horseshoe kidney in approximately 20% of cases. The relative risk for a person with horseshoe kidney to develop this tumor is estimated at 82 times the general population. Was first reported by Resnick in 1966 in a patient with carcinoid syndrome, however, most organ-confined tumors do not produce carcinoid syndrome, which resembles carcinoids in other organ systems.
Pathology
Pathology
Macroscopically, it presents as a solitary well-circumscribed, moderately firm tumor with a lumpy appearance. The color is variable; the appearance is consistent with variable focal hemorrhage and calcification. The histopathologic features appear similar to carcinoid tumors in other organ systems. The cells are uniform in size and arranged in a trabecular pattern. Have small nuclei with "salt and pepper" chromatin and eosinophilic cytoplasm. Immunohistochemical staining is positive for chromogranin, neuron-specific enolase, and keratin. Variable positivity for serotonin, pancreatic polypeptide, prostatic acid phosphatase, and vasoactive intestinal polypeptide have been reported.
Clinical Presentation
Most patients present with an asymptomatic mass, however, can also present with abdominal pain, mass, or hematuria. Alternative source differential diagnosis is indicated when a lesion is found in the kidney, due to the rarity of primary renal carcinoid. carcinoid symptoms are present in less than 10% of patients at presentation.
The median age at diagnosis is 50 years, without sex predilection. The TC is presented as a circumscribed solid mass with occasional calcification or cystic changes. Some authorities have suggested that an octreotide scan can contribute to accurate staging
diagnosis.
Treatment and Prognosis
The median age at diagnosis is 50 years, without sex predilection. The TC is presented as a circumscribed solid mass with occasional calcification or cystic changes. Some authorities have suggested that an octreotide scan can contribute to accurate staging
diagnosis.
Treatment and Prognosis
Because of the rarity of the disease, clinical outcome is difficult to predict. This is also complicated by the fact that a significant proportion of patients with metastatic disease have prolonged survival. Complete excision of localized disease in the kidney seems to have good long-term results, with reports available are limited. Carcinoid tumors arising in horseshoe kidneys tend to have a more indolent course.
Carcinoid crisis secondary to the release of vasoactive substances may occur with the biopsy or surgical resection of the tumor and can be managed with somatostatin. In patients with a solitary metastasis, especially in the liver, it would be appropriate to consider resection of primary tumor with metastasis, due to the lack of effective systemic treatment options. Radiation is effective for short-term relief. The scant information on therapy for metastatic renal carcinoid is available. In patients with carcinoid syndrome, control of symptoms with somatostatin or octreotide analogs as possible.
For people with metastatic disease, systemic treatment options are based on clinical trials in patients with gastrointestinal carcinoid tumors. Interferon produces tumor regression (15%) and biochemical responses in patients with metastatic disease. Combination chemotherapy is of limited value. In a cooperative oncology group of the East (ECOG) trial, 118 patients with metastatic carcinoid tumor were randomized to treatment with streptozotocin in combination with cyclophosphamide or 5-fluorouracil (5-FU). Objective response rates among evaluable patients treated with the combination of 5-FU was 33% and the combination of cyclophosphamide 26%, with substantial toxicity in both regimens.