Pulmonary micropapillary-type adenosquamous carcinoma sharing epidermal growth factor receptor mutation in adenocarcinoma and squamous cell carcinoma

Mucinous tubular and spindle cell carcinoma with a high nuclear grade and micropapillary pattern: A case report

Mucinous tubular and spindle cell carcinoma (MTSCC) is rare in renal cell carcinoma (RCC) and usually demonstrates a low nuclear grade and a better prognosis compared with other RCCs. The authors present a case report of MTSCC containing an area of Fuhrman nuclear grade 3, in addition to an area with a micropapillary pattern. An 82-year-old man consulted a hospital due to macrohematuria, and a tumor in the right kidney was detected. The tumor was resected and histologically examined. The tumor consisted of various growth patterns: Elongated tubular structure, a papillary structure containing a micropapillary pattern and solid pattern with spindle cells. The tumor cells demonstrated Fuhrman nuclear grades 2 and 3. Invasion into the lymph vessel and metastasis into the regional lymph node were observed. Thus, the tumor was diagnosed as a high grade MTSCC. Five months following resection, a computed tomography scan suggested metastasis of the tumor into the para-aortic lymph nodes and liver, and the patient succumbed to brain metastasis. When MTSCC of kidney is observed, careful histological observation is important to avoid missing a high nuclear grade area.

Pulmonary micropapillary-type adenosquamous carcinoma sharing epidermal growth factor receptor mutation in adenocarcinoma and squamous cell carcinoma

Adenosquamous lung carcinoma (AdSqLC) has a worse prognosis than adenocarcinoma (ADC) or squamous cell carcinoma (SQCC). Micropapillary pattern in lung ADC is an additional poor prognostic factor. We describe a rare case of AdSqLC with epidermal growth factor receptor (EGFR) mutation in both the micropapillary‐ADC and SQCC components, showing long‐term response to gefitinib. A 60‐year‐old woman underwent right lower lobectomy for primary lung cancer. Histopathological examination demonstrated adenosquamous carcinoma comprising micropapillary‐ADC and moderately differentiated SQCC. EGFR exon 19 deletions mutation was detected in both the ADC and SQCC components. Gefitinib was administered for multiple metastatic recurrences on bilateral lung, resulting in remarkable shrinkage of visible lesions. The efficacy of gefitinib lasted for 31 months after the induction. AdSqLCs harbouring the EGFR mutation in both the ADC and SQCC components may well benefit from EGFR tyrosine kinase inhibitors, especially when they contain micropapillary‐ADC component that correlates with frequent EGFR mutations.