porokeratosis is a genetic disease transmitted as an autosomal dominant trait featuring abnormal epidermal keratinization , which is histologically characterized by the presence of cornoid lamella . since then many variants of porokeratosis have been described , each with differing morphology , distribution , and clinical course . familial adenomatous polyposis ( fap ) is characterized by numerous adenomatous colorectal polyps that have an intrinsic tendency to progress to adenocarcinoma . fap with extra - intestinal lesions such as epidermoid cysts , osteomas , desmoid tumors , dental anomalies is called gardner 's syndrome . the association of porokeratosis of mibelli with gardner 's syndrome is extremely rare without any recorded cases in the literature , prompted us to report this case . an 18-year - old female of low socio - economic status presented to skin opd with complaints of multiple skin lesions all over the body and swellings on the face , scalp , and extremities of five years duration . lesions started to develop on the scalp insidiously , and later on left mandible , face , and extremities . clinical examination of the patient revealed multiple skin plaques present on the face , forearms , back and both lower extremities with elevated margin with a prominent deep furrow and central part showed normal skin [ figure 1 ] . fluctuant skin swellings were observed on the scalp and back of trunk , with punctum [ figure 2 ] . over the body of left ramus of mandible a clinical diagnosis of porokeratosis of mibelli , epidermoid cysts , and osteoma of mandible was made . family history of the index case revealed father had dysphagia , pain abdomen with episodes of bleeding per rectum , and ultimately died of us suspected gastrointestinal ( git ) origin malignancy . biopsy of the skin plaques , along with the excision biopsy of cystic swelling over scalp and bony hard swelling of left mandible was done . because of the family history and clinical presentation ( sebaceous cysts and osteoma ) , a colonoscopy was done which revealed a solitary rectal polyp of 1  1.5 cm in size situated 7.0 cm from anal verge . porokeratosis of mibelli histopathological examination of the plaque lesions of skin revealed a keratin filled invagination of the epidermis , the center of which showed parakeratotic column ( interpreted as cornoid lamella ) . bone lesion showed the histopathology of a benign osteoma showing mature osteocytes [ figure 5 ] . histopathological examination of rectal polyp showed hyperplastic polyp of rectal mucosa with focal adenomatous change , mild nonspecific inflammation , cystic change , congested vessels with no evidence of malignancy [ figure 6 ] . parakertotic column ( cornoid lamella ) in porokeratosis mibelli , ( h and e , 100 ) osteoma with mature osteocytes ( h and e , 200 ) hyperplastic polyp of rectal mucosa with focal adenomatous change ( h and e , 100 ) the clinical picture , family history and multiple lesions diagnosed histologically in the index patient , we contemplated the possibility of porokeratosis of mibelli with an evolving gardner 's syndrome . gardner 's syndrome start with a few polyps in the 10 - 20 year age group and develop into its full blown clinical picture by the fourth decade of the patient , with an intrinsic tendency to progress to adenocarcinoma . it is caused by a germline mutation in the adenomatous polyposis coli ( apc ) gene located on the long arm of chromosome 5 . the mandible is the most common location ; however , osteomas may occur in the skull and the long bone . osteomas precede the clinical and radiographic evidence of colonic polyposis , therefore , they may be sensitive markers for the disease . porokeratosis is a heterogeneous group of disorders characterized by distinct clinical findings of a keratotic ridge with a central groove that corresponds to the cornoid lamellae on histology . etiopathogenesis of porokeratosis is unknown but genetic inheritance as well as acquired form has been reported . heredity , immunosuppression , infection , and ultraviolet rays have been found to play a role in the causation of porokeratosis . no specific candidate gene has been found . however , genetic loci of disseminated superficial actinic porokeratosis have been detected in the region 12q23.2 - 24.1 ( dsap 1 ) and 15q25.1 - 26.1 ( dsap 2 ) . recently , another loci has been found within an 8.2 cm or 11.9 mb region between markers d1s438 and d1s464 ( dsap 3 ) . larger lesions have higher malignant potentiality , particularly , the giant variety that is most frequently reported to show malignant transformation . malignancies reported in porokeratosis are squamous cell carcinoma , bowen 's disease , basal cell carcinoma , diffuse large b - cell lymphoma , etc . porokeratosis in association with lichen planus , diabetes mellitus , cap syndrome ( craniosynostosis , anal anomalies , and porokeratosis ) , bloom 's syndrome , cystic fibrosis etc , have been reported.[711 ] to the best of our knowledge this is the first case reported of porokeratosis of mibelli with gardener 's syndrome .