Clinical Description
FH tumor predisposition syndrome is characterized by cutaneous leiomyomas, uterine leiomyomata (fibroids), and/or renal tumors. Pheochromocytoma and paraganglioma have also been described in a small number of families. Affected individuals may have a single, multiple, or no cutaneous leiomyomas, typically one or more uterine fibroids, and/or a single or no renal tumors. Rarely, individuals may develop multifocal renal tumors. Disease severity shows significant intra- and interfamilial variation [Wei et al 2006].
Cutaneous leiomyomas. Clinically, cutaneous leiomyomas present as firm skin-colored to light brown-colored papules and nodules. These cutaneous lesions occur at a mean age of 30 years (range: age 10-77 years) [Muller et al 2017] and tend to increase in size and number with age. Affected individuals often note that the skin lesions are painful or sensitive to light touch and/or cold temperature [Lehtonen 2011].
Histologically, proliferation of bundles of smooth muscle fibers with central blunt-edged nuclei is observed [Toro et al 2003].
Cutaneous leiomyosarcoma. In a series of 182 individuals with FH tumor predisposition syndrome from 114 families, three individuals developed skin leiomyosarcoma [Muller et al 2017]. Due to changes in diagnostic criteria and nomenclature, lesions previously called leiomyosarcoma may have been atypical smooth-muscle neoplasms/leiomyomas [Kraft & Fletcher 2011].
Uterine leiomyomas (uterine fibroids). Women with FH tumor predisposition syndrome have more uterine fibroids and onset at a younger age than women in the general population. The age at identification of fibroids ranges from 18 to 53 years (mean: age ~30 years) [Lehtonen 2011]. Uterine fibroids in women with FH tumor predisposition syndrome are usually large and numerous and associated with irregular menses, menorrhagia, or pain [Lehtonen 2011]. Women with FH tumor predisposition syndrome often undergo hysterectomy or myomectomy for symptomatic uterine fibroids at a younger age. In one series, 59 of 114 women (52%) with FH tumor predisposition syndrome had myomectomy or hysterectomy with median age of 35 (range 25-58) [Muller et al 2017].
Among a cohort of 2,060 women with uterine smooth muscle tumors, a prospective screening program identified a tumor with FH-deficient morphology in 30 individuals (1.4%). Histologic criteria for FH-deficient morphology included alveolar pattern edema and staghorn-shaped blood vessels under low magnification, and smooth muscle cells with a macro-nucleolus surrounded by a halo and eosinophilic globules seen under high magnification [Rabban et al 2019]. Ten women with a tumor with this morphology elected to proceed with germline FH molecular testing; of these, five were found to have a germline FH pathogenic variant, suggesting that uterine tumor histology could be used to identify individuals with FH tumor predisposition syndrome [Rabban et al 2019].
Uterine leiomyosarcoma. Six women with a germline FH pathogenic variant and uterine leiomyosarcoma have been reported in the Finnish population; including three individuals with an additional pathogenic variant identified in tumor tissue, and one individual with isolated leiomyosarcoma, decreased FH activity, but no pathogenic variant identified on tumor tissue testing [Lehtonen et al 2006, Ylisaukko-oja et al 2006b]. However, uterine leiomyosarcoma has not been reported in other cohorts [Muller et al 2017]. Due to changes in diagnostic criteria and nomenclature, lesions previously called leiomyosarcoma may in fact be atypical smooth-muscle neoplasms/leiomyomas [Muller et al 2017].
Renal cancer. Most renal tumors are unilateral and solitary; in a few individuals, they are multifocal. The symptoms of renal cancer may include hematuria, lower back pain, and a palpable mass. However, a large number of individuals with renal cancer are asymptomatic. Furthermore, not all individuals with FH tumor predisposition syndrome present with or develop renal cancer.
Of 182 individuals with FH tumor predisposition syndrome from 114 families, 34 (19%) were diagnosed with RCC(s). The median age at diagnosis was 40 years. Of 31 individuals with follow-up data available, 82% developed metastatic disease: 16 (47%) presented with metastatic RCC (de novo metastatic disease) and another 12 (35%) became metastatic within three years. Among individuals with metastatic RCC, median survival was 18 months [Muller et al 2017].
FH tumor predisposition syndrome is associated with a spectrum of renal tumors including type 2 papillary, undefined papillary, unclassified, tubulocystic, and collecting-duct carcinoma [Wei et al 2006].
FH-related RCC often shows loss of FH staining and positive staining for S-(2-succino) cysteine. Immunohistochemistry cannot distinguish between tumors due to FH tumor predisposition syndrome and those due to biallelic somatic pathogenic variants.
The Cancer Genome Atlas has additionally reported a CpG island methylator phenotype (CIMP) as the signature FH-associated RCC [Cancer Genome Atlas Research Network 2016].
Pheochromocytoma and paraganglioma. In 2014, two studies aimed at identifying new pheochromocytoma and paraganglioma susceptibility genes identified FH germline pathogenic variants in seven of 570 affected individuals [Castro-Vega et al 2014, Clark et al 2014]. Subsequently, two individuals with FH tumor predisposition syndrome from a French cohort (1%) were diagnosed with pheochromocytoma [Muller et al 2017]. The lifetime risks for pheochromocytoma and paraganglioma are unknown.
Other. In a Finnish population-based study of FH tumor predisposition syndrome, four individuals with breast cancer and one individual with bladder cancer were identified. In three of three breast cancers examined, loss of the wild type FH allele was noted [Lehtonen et al 2006].
While other tumors have been described in individuals with germline FH pathogenic variants, further data will be needed to determine whether these are FH-related tumors [Lehtonen et al 2006, Ylisaukko-oja et al 2006a].
Genotype-Phenotype Correlations
No correlation is observed between specific FH pathogenic variants and the occurrence of cutaneous lesions, uterine fibroids, or renal cancer [Wei et al 2006].
FH pathogenic variants reported in families with paraganglioma include the following missense and splice site variants: p.Ala117Pro, c.268-2A>G, p.Thr381Ile, p.Ala194Thr, p.Asn329Ser, p.Cys43Tyr, p.Glu53Lys [Castro-Vega et al 2014, Clark et al 2014].
Pathogenic variant c.700A>G; p.Thr234Ala has been identified in approximately ten families with paraganglioma/pheochromocytoma with and without renal cell carcinoma [Author, personal communication].
Nomenclature
Historically, the predisposition to the development of cutaneous leiomyomas was referred to as multiple cutaneous leiomyomatosis (MCL/MCUL).
Reed et al [1973] described two kindreds in which multiple members exhibited cutaneous leiomyomas and uterine leiomyomas inherited in an autosomal dominant manner. Subsequently, the association of cutaneous and uterine leiomyomas was referred to as Reed's syndrome.
The association of cutaneous and uterine leiomyomas with renal cancer was described in two Finnish families [Launonen et al 2001]. The name hereditary leiomyomatosis and renal cell cancer (HLRCC) was designated.
Germline FH pathogenic variants are now known to be associated with a predisposition to a variety of tumors. The term "FH tumor predisposition syndrome" acknowledges this emerging understanding.