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Genetics of Skin Cancer (PDQ®): Genetics - Health Professional Information [NCI] - Basal Cell Carcinoma

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The diagnosis of BCNS is typically based upon characteristic clinical and radiologic examination findings. Several sets of clinical diagnostic criteria for BCNS are in use (refer to Table 1 for a comparison of these criteria).[69,70,71] Although each set of criteria has advantages and disadvantages, none of the sets have a clearly superior balance of sensitivity and specificity for identifying mutation carriers. PTCH1 mutations are found in 60% to 85% of patients who meet clinical criteria.[72,73] Most notably, BCNS is associated with the formation of both benign and malignant neoplasms. The strongest benign neoplasm association is with ovarian fibromas, diagnosed in 14% to 24% of females affected by BCNS.[66,70,74] BCNS-associated ovarian fibromas are more likely to be bilateral and calcified than sporadic ovarian fibromas.[75]

Other associated benign neoplasms include gastric hamartomatous polyps,[76]congenital pulmonary cysts,[77] cardiac fibromas,[78] meningiomas,[79,80] craniopharyngiomas,[81] fetal rhabdomyomas,[82] leiomyomas,[83] mesenchymomas,[84] and nasal dermoid tumors. Development of meningiomas and ependymomas occurring postradiation therapy has been documented in the general pediatric population; radiation therapy for syndrome-associated intracranial processes may be partially responsible for a subset of these benign tumors in individuals with BCNS.[85,86,87] Radiation therapy of medulloblastomas may result in many cutaneous BCCs in the radiation ports. Similarly, treatment of BCC of the skin with radiation therapy may result in induction of large numbers of additional BCCs.[65,66,83]

The diagnostic criteria for BCNS are described in Table 1 below.

Table 1. Comparison of Diagnostic Criteria for Basal Cell Nevus Syndrome (BCNS)

Evans et al. 1993[69]Kimonis et al. 1997[70]Veenstra-Knol et al. 2005[71]
a Two major criteria or one major and two minor criteria needed to meet the requirements for a BCNS diagnosis.[69,70,71]
BCC = basal cell carcinoma.
Major Criteriaa
>2 BCCs or 1 BCC diagnosed before age 30 y or >10 basal cell nevi>2 BCCs or 1 BCC diagnosed before age 20 y>2 BCCs or 1 BCC diagnosed before age 20 y
Histologically proven odontogenic keratocyst or polyostotic bone cystHistologically proven odontogenic keratocystHistologically proven odontogenic keratocyst
≥3 palmar or plantar pits≥3 palmar or plantar pits≥3 palmar or plantar pits
Ectopic calcifications, lamellar or early (diagnosed before age 20 y) faux calcificationsBilamellar calcification of faux cerebriEctopic calcification (lamellar or early faux cerebri)
Family history of BCNSFirst-degree relative with BCNSFamily history of BCNS
(Rib abnormalities listed as minor criterion; see below.)Bifid, fused, or splayed ribsBifid, fused, or splayed ribs
Minor Criteria
Occipital-frontal circumference >97th percentile and frontal bossingMacrocephaly (adjusted for height)Macrocephaly (>97th percentile)
Congenital skeletal abnormalities: bifid, fused, splayed, or missing rib or bifid, wedged, or fused vertebraeBridging of sella turcica, vertebral abnormalities (hemivertebrae, fusion or elongation of vertebral bodies), modeling defects of the hands and feet, or flame-shaped lucencies of hands and feetBridging of sella turcica, vertebral abnormalities (hemivertebrae, fusion or elongation of vertebral bodies), modeling defects of the hands and feet
(Rib abnormalities listed as major criterion; see above.) (Rib abnormalities listed as major criterion; see above.)
Cardiac or ovarian fibromaOvarian fibromaCardiac or ovarian fibroma
MedulloblastomaMedulloblastomaMedulloblastoma
Congenital malformation: cleft lip and/or palate, polydactyly, cataract, coloboma, microphthalmiaCleft lip or palate, frontal bossing, moderate or severe hypotelorismCleft lip and/or palate, polydactyly
 Sprengel deformity, marked pectus deformity, marked syndactylySprengel deformity, marked pectus deformity, marked syndactyly
Lymphomesenteric cysts  
  Eye anomaly: cataract, coloboma, microphthalmia
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