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Ann Diagn Pathol. 2014 Jun;18(3):171-6. doi: 10.1016/j.anndiagpath.2014.03.002. Epub 2014 Mar 29.

Intratumoral peripheral small papillary tufts: a diagnostic clue of renal tumors associated with Birt-Hogg-Dubé syndrome.

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Department of Diagnostic Pathology, Kochi Red Cross Hospital, Kochi, Japan. Electronic address:
Department of Molecular Pathology, Yokohama City University Graduate School of Medicine, Yokohama, Japan.
Division of Pathology, JA Hokkaido Koseiren Sapporo Kosei Hospital, Sapporo, Japan.
Department of Advanced Diagnosis, Division of Pathology, Nagoya Medical Center, Nagoya, Japan.
Department of Diagnostic Pathology, Kobe University Hospital, Kobe, Japan.
Division of Surgical Pathology, University of Fukui Hospital, Fukui, Japan.
Division of Pathology, Tokushima University Hospital, Tokushima, University of Tokushima Graduate School, Tokushima, Japan.
Department of Urology, Institute of Health Biosciences, University of Tokushima Graduate School, Tokushima, Japan.
Department of Diagnostic Pathology, Chiba University Graduate School of Medicine, Chiba, Japan.
Department of Pathology, Charles University in Prague, Faculty of Medicine, Plzen, Czech Republic.


In this article, we searched for the common histologic characteristic of renal tumors in patients with Birt-Hogg-Dubé syndrome (BHDS). We selected 6 patients with histologically confirmed renal tumor in BHDS. Germline FLCN gene mutation has been identified in 5 patients. Multifocality and bilaterality of the renal tumors were pathologically or radiologically confirmed in 5 and 2 cases, respectively. Histologic subtypes of the dominant tumor included 3 previously described hybrid oncocytic tumors, one composite chromophobe/papillary/clear cell renal cell carcinoma (RCC) and one unclassified RCC resembling hybrid chromophobe/clear cell RCC. In one case, chromophobe RCC and clear cell RCC were separately observed. Small papillary lesions located in the peripheral area of the tumor, which we designated as intratumoral peripheral small papillary tufts, were identified in all patients. In conclusion, multifocality/bilaterality of renal tumors, discordance of histologic subtypes, and the presence of intratumoral peripheral small papillary tufts may be important clues to identify BHDS-associated renal tumors.


Birt-Hogg-Dubé syndrome; Intratumoral peripheral small papillary tufts; Renal tumor

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