Primary Signet Ring Cell Carcinoma of the Lung with Cerebellar Metastasis Showing Full Response to Cisplatin and Docetaxel Therapy

Introduction. Primary signet ring cell carcinoma (SRCC) of the lung is a very rare disease. We describe a new case of primary SRCC of the lung with cerebellar metastasis, which responded well to the therapeutic approach with cisplatin and docetaxel. Case Report. A 41-year-old female patient (nonsmoker) was consulted to our oncology outpatient clinic after cerebellar metastasectomy. The histopathological diagnosis was SRCC metastasis. The primary tumor was unknown. The PET-CT imaging showed a hypermetabolic mass in the right middle lobe of the lung and hypermetabolic mediastinal lymph node stations. Oesophagogastroduodenoscopy and colonoscopy showed no evidence of gastrointestinal system tumor. The clinical diagnosis of primary SRCC of the lung was made and the administration of six rounds of cisplatin and docetaxel treatment was planned. After the chemotherapy the PET-CT scan to evaluate the therapy response showed full metabolic regression of the primary tumor and the mediastinal lymph nodes. There was no evidence of new metastasis. Conclusion. Primary SRCC of the lung is a very rare disease with poor prognosis. There are not many cases in literature and no standardized chemotherapy protocols. Cisplatin and docetaxel may be a good treatment option. 1. Introduction Primary SRCC of the lung is a very rare disease. First described by Kish et al. in 1989, it is reported that incidence of primary SRCC of the lung varies from 0.14% to 1.9% of all lung cancers [1]. The largest series was taken by Tsuta et al. in which 39 of 2640 surgically resected primary lung carcinomas showed SRCC components. Mean age of the patients was 54.6 years, male to female ratio was 1.16？:？1.00, and 26 patients (66.7%) were smokers. The size of the SRCC component of the tumor positively correlated with the aggressiveness of the tumor and poor outcome. The 5-year survival was 28% [2]. 2. Case A 41-years-old female patient (nonsmoker) was consulted to our oncology outpatient clinic by the neurosurgery clinic after a cerebellar metastasectomy. The preop CT scan showed a right cerebellar hypodense lesion with the dimension of 5 × 5？cm (Figure 1). Figure 1: The preop CT scan showed a right cerebellar hypodens lesion. The histopathological examination of the metastasectomy material showed SRCC metastasis with positive immunostaining for CEA, CK 7, and TTF-1. The immunostaining with CK 20, ER, COX2, CK 14, CDX2, and MUC2 was negative. The histopathological morphology was shown Figures 2(a), 2(b), and 2(c). Figure 2: (a) Malign epithelial infiltration in the cerebellum with signet-ring