Birt-Hogg-Dubé syndrome: metalloproteinase activity and response to doxycycline

Birt-Hogg-Dubé syndrome. State-of-the-art review with emphasis on pulmonary involvement

BACKGROUND

Birt-Hogg-Dubé syndrome (BHDS) is a rare, inherited autosomal-dominant disorder characterized by the development of cutaneous lesions, renal tumors, pulmonary cysts, and spontaneous pneumothorax. The gene responsible for BHDS is located on the short arm of chromosome 17 (17p11.2) and codes for the protein folliculin, which is believed to be an oncogene suppressor protein.

METHODS

We reviewed currently published literature on the main characteristics of BHDS.

RESULTS

Pulmonary cysts and spontaneous pneumothorax are often the presenting manifestations that lead to a final diagnosis in family members affected by the syndrome.

CONCLUSIONS

Certain imaging characteristics of pulmonary cysts, including size and location, can suggest the diagnosis of BHDS based on chest computed tomography alone. The main concern in patients with BHDS is the increased risk of renal carcinoma. The aim of this review is to describe the main pathological, clinical, and imaging aspects of BHDS, ranging from its genetic basis to treatment, with emphasis on pulmonary involvement.

Oncocytoma-like renal tumor with transformation toward high-grade oncocytic carcinoma: a unique case with morphologic, immunohistochemical, and genomic characterization

Renal oncocytoma is a benign tumor with characteristic histologic findings. We describe an oncocytoma-like renal tumor with progression to high-grade oncocytic carcinoma and metastasis. A 74-year-old man with no family history of cancer presented with hematuria. Computed tomography showed an 11 cm heterogeneous multilobulated mass in the right kidney lower pole, enlarged aortocaval lymph nodes, and multiple lung nodules. In the nephrectomy specimen, approximately one third of the renal tumor histologically showed regions classic for benign oncocytoma transitioning to regions of high-grade carcinoma without sharp demarcation. With extensive genomic investigation using single nucleotide polymorphism-based array virtual karyotyping, multiregion sequencing, and expression array analysis, we were able to show a common lineage between the benign oncocytoma and high-grade oncocytic carcinoma regions in the tumor. We were also able to show karyotypic differences underlying this progression. The benign oncocytoma showed no chromosomal aberrations, whereas the high-grade oncocytic carcinoma showed loss of the 17p region housing FLCN (folliculin [Birt-Hogg-Dubé protein]), loss of 8p, and gain of 8q. Gene expression patterns supported dysregulation and activation of phosphoinositide 3-kinase (PI3K)/v-akt murine thymoma viral oncogene homolog (Akt), mitogen-activated protein kinase (MAPK)/extracellular-signal-regulated kinase (ERK), and mechanistic target of rapamycin (serine/threonine kinase) (mTOR) pathways in the high-grade oncocytic carcinoma regions. This was partly attributable to FLCN underexpression but further accentuated by overexpression of numerous genes on 8q. In the high-grade oncocytic carcinoma region, vascular endothelial growth factor A along with metalloproteinases matrix metallopeptidase 9 and matrix metallopeptidase 12 were overexpressed, facilitating angiogenesis and invasiveness. Genetic molecular testing provided evidence for the development of an aggressive oncocytic carcinoma from an oncocytoma, leading to aggressive targeted treatment but eventual death 39 months after the diagnosis.