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Eble JN, Sauter G., Epstein JI, Sesterhenn IA - iarc

Eble JN, Sauter G., Epstein JI, Sesterhenn IA - iarc

Eble JN, Sauter G., Epstein JI, Sesterhenn IA - iarc

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A<br />

B<br />

Fig. 1.11 A Multiple cutaneous leiomyomas in a female HLRCC patient. B Fumarate hydratase (FH) gene mutations in HLRCC and FH deficiency. Mutated codons identified<br />

in the families with RCC and/or uterine leiomyosarcoma are indicated.<br />

as multiple firm, skin-coloured nodules<br />

ranging in size from 0.5-2 cm. Uterine<br />

leiomyomas in HLRCC are often numerous<br />

and large. Cutaneous leiomyomas are<br />

composed of interlacing bundles of<br />

smooth muscle cells with centrally located<br />

blunt-ended nucleus. Uterine leiomyomas<br />

are well-circumscribed lesions with firm<br />

and fibrous appearance. Histologically,<br />

they are composed of interlacing bundles<br />

of elongated, eosinophilic smooth muscle<br />

cells surrounded by well-vascularized<br />

connective tissue. Leiomyomas with atypia<br />

may also occur.<br />

Leiomyosarcoma of the uterus<br />

Predisposition to uterine leiomyosarcoma<br />

is detected in a subset of HLRCC<br />

families (3 out of 105 families)<br />

{1450,1469}. The cases have been<br />

diagnosed at 30-39 years. Uterine<br />

leiomyosarcomas invade the adjacent<br />

myometrium and are not well demarcated<br />

from normal tissue. The tumours<br />

are densely cellular and display spindle<br />

cells with blunt-ended nuclei,<br />

eosinophilic cytoplasm, and a variable<br />

degree of differentiation.<br />

Genetics<br />

Gene structure and function<br />

FH is located in chromosome 1q42.3-<br />

q43, consists of 10 exons, and encodes<br />

a 511 amino acid peptide. The first exon<br />

encodes a mitochondrial signal peptide.<br />

{661,662,2623}, but processed FH (without<br />

the signal peptide) is present also in<br />

the cytosol. Mitochondrial FH acts in the<br />

tricarboxylic acid (Krebs) cycle catalyzing<br />

conversion of fumarate to malate. FH<br />

is also known to be involved in the urea<br />

cycle. However, the role of cytosolic FH<br />

is still somewhat unclear. Biallelic inacti-<br />

A<br />

Fig. 1.12 Hereditary leiomyoma renal cell carcinoma (HLRCC). A Renal cell carcinoma from a 50 year old female patient displaying papillary architecture resembling<br />

papillary renal cell carcinoma, type 2 (H&E staining, magnification x10). B Thick papillae are covered by tall cells with abundant cytoplasm, large pseudostratified<br />

nuclei and prominent nucleoli.<br />

B<br />

Familial renal cell carcinoma<br />

19

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