Mucinous bronchioloalveolar carcinoma of lung with a rhabdoid component?report of a case and review of the literature

Transition From Distinct Types of KRAS Mutation-Harboring Multifocal Lung Adenocarcinoma to Rhabdoid Tumor: A Longitudinal Follow-Up

BACKGROUND Rhabdoid tumor (RT) of the lung is a rare and aggressive malignancy. The origin of and the mutation responsible for RT are entirely unknown. The distinction between RT associated with subtypes of lung cancer and SMARCA4-deficient thoracic sarcomas is also unknown. CASE REPORT Three pulmonary subsolid nodules in the right S6, left S6, and left S8 were identified in a 78-year-old Japanese woman. At 3 and 9 months later, a chest CT showed unchanged sizes, but at 15 months the development of a 37-mm mass in the right S6 was observed. The patient's systemic condition deteriorated rapidly, and she died 1 month later. An autopsy revealed that the mass consisted of 90% RT and 10% lung adenocarcinoma. There were another 2 adenocarcinoma lesions in the left lung. KRAS mutation analyses revealed the same KRAS mutation (G12D) in the adenocarcinoma and RT components in the identical mass and metastatic RT, indicating that all of these components had the same clonality. A different KRAS mutation in each of the 3 adenocarcinoma lesions was detected (right S6: G12D, left S6: A59G, left S8: G12C), indicating that the multiple adenocarcinoma lesions were truly multifocal lung adenocarcinoma. The adenocarcinoma and RT components retained SMARCA4 expression. CONCLUSIONS This is the first evidence of RT originating from multifocal lung adenocarcinoma. KRAS mutation is thought to be responsible for the RT's emergence via the epithelial-mesenchymal transition. Patients with multiple subsolid nodules should be followed closely; aggressive surgical intervention should be considered given concerns about the evolution of this aggressive malignancy.

Atypical teratoid/rhabdoid tumor of the pineal region in an adult

An atypical teratoid/rhabdoid tumor (AT/RT) is a highly malignant embryonal tumor most often occurring in the posterior fossa in children younger than 3 years of age. Adult cases of AT/RT are very rare, and 27 cases with a diagnosis of either AT/RT or (malignant) rhabdoid tumor have been reported to date. The authors report an adult case of an AT/RT occurring in the pineal region with molecular cytogenetic and immunohistochemical confirmation. A 33-year-old woman presented with a 2-month history of headache and blurred vision progressing to diplopia, and was admitted emergently due to deteriorating mental status. An MR image showed a heterogeneously enhancing mass involving the posterior third ventricle and pineal region with mild hydrocephalus. She underwent a subtotal resection of the tumor and was then treated with chemoradiation. Thirteen months after surgery, she was still alive with radiological evidence of recurrence/residual lesions. Histological sections showed epithelioid cellular sheets of rhabdoid tumor cells with scattered mitotic figures. Immunohistochemically, the tumor cells were diffusely and strongly positive for epithelial membrane antigen and vimentin, and showed focal expression of glial fibrillary acidic protein, pancytokeratin, and neurofilament protein. Loss of nuclear immunoreactivity for INI1 protein was observed. Fluorescence in situ hybridization analysis showed monosomy 22. Histologically, this tumor consisted exclusively of epithelioid tumor cells with rhabdoid features. The differential diagnoses include rhabdoid glioblastoma, metastatic carcinoma, and rhabdoid meningioma. Molecular testing to identify monosomy 22 or deletions of the chromosome 22q11 containing the INI1/hSNF5 gene and/or immunohistochemical staining with INI1 antibody is of great importance for the diagnosis of this tumor.