cutaneous horn ( synonyms ; cornu cutaneum : cornu humanum ) is a conical , hyperkeratotic protrusion that often resembles an animal horn . the term  cutaneous horn  is a morphologic designation referring to unusually cohesive keratinized material and not a true pathologic diagnosis . the earliest documented case of cutaneous horn , or cornu cutaneum , was that of an elderly welsh woman in london who was displayed commercially as an anomaly of nature in 1588 . there were several other accounts of cutaneous horns in the sixteenth and seventeenth centuries , including those described by danish anatomist thomas bartholin in 1670 . illustrations from that time portray these growths as grotesque , and numerous natural and supernatural theories arose regarding their etiology . for centuries cutaneous horns have been a subject of curiosities and controversies . in the late eighteenth century , the london surgeons everard home and his brother - in - law john hunter are generally credited with the characterization of cutaneous horns as a medical disorder . though cutaneous horn has been described at various sites , horn over the penis is very rare and represents the most unusual site . the first case report of a penile horn was published as early as 1854 . since then there has been sporadic reporting of cases by dermatologists , surgeons and urologists mainly for curiosity and various conditions which may present as a penile horn . cutaneous horn occurs mainly in individuals who are above 50 years of age and penile horns are no exception to this rule . they are common in males after 50 years and probably coincide with the age group of occurrence of penile cancer . to this date lowe and mc cullogh reported that penile horn may be benign in 4256% of cases , premalignant in 2237% or frankly malignant in 2022% . cutaneous horn is a morphologic designation for a protuberant mass of keratin produced by unusual cohesiveness of keratinized material . it is rather intriguing to note that why only few patients develop penile horn when compared with other patients with similar disease . the roles of chronic irritation , phimosis , surgical trauma and radiotherapy that have been implicated in penile horn formation have also been found to predispose to carcinoma penis . the emphasis is on the long - standing phimosis with chronic , prolonged preputial inflammation ; however , it has also been seen in circumcised men . adult circumcision has been found to precede horn formation by a period ranging from 2 weeks to a year . the analysis of the cases reported so far do not reveal any common factor that predisposes to the development of horn over the underlying pathology . the occurrence of horn in different disorders ranging from benign viral disease to malignant carcinoma further augments the view that the keratinous growth probably represents a reactionary event , which does not depend on the underlying pathology . pseudoepitheliomatous , keratotic and micaceous balanitis is another rare disease , which has been found to be associated with penile horn . it was , originally described by jacob and civatte who considered it to be benign . similarly , verrucous carcinoma is another tumor which has been found to be associated with penile horn . this tumor is a highly keratinizing tumor , and this probably predisposes for penile horn formation . the progression of cutaneous horn to malignancy though has been reported probably represents the manifestation of underlying tumor . causes of penile horn the role of human papillomavirus ( hpv ) in penile carcinoma is well studied . the hpv 16 and 18 are implicated as the causative agents . in penile horns that arise from malignancies such as verrucous carcinoma , penile horns present as elongated , keratinous , white or yellowish projections that range from a few millimeters to centimeters in size arising from the glans penis [ figures 1 and 2 ] . traumatic breakage of the horn is rare and can occur due to the projectile nature of the growth . hard keratotic mass arising from glans penis the patients seek treatment for the disfigurement and difficulty posed during intercourse . in general horns arising from malignant lesions tend to be harder on their bases due to the inflammatory process . their surface is rough , irregular , laminated or fissured , the ends pointed , blunt or clubbed . the color varies ; it is usually grayish - yellow , but may be even blackish . commonly they are small in size , a fraction of an inch or an inch or thereabouts in length , but exceptionally attain considerable proportions . the base , which rests directly on the skin , may be broad , flattened , or concave , with the underlying and adjacent tissues normal or the papill hypertrophied ; and in some cases there is more or less inflammation , which may be followed by suppuration . they are , as a rule , painless but become painful when knocked or irritated . the histopathology of the cause is diagnostic in most cases . from the histopathological point of view cutaneous horn can be classified as benign , premalignant and malignant based on the origin . it consists of closely agglutinated epidermic cells , forming small columns or rods . in the columns they have their starting - point in the rete mucosum , either from that lying above the papilla or that lining the follicles and glands . keratinous mass overlying the epidermis ( 40 ) part two is the underlying pathology beneath the keratotic mass . though histopathology is diagnostic certain other investigations are required particularly in patients with underlying malignancy . approximately one - third of penile cutaneous horns are associated with an underlying malignancy , and so magnetic resonance imaging is helpful when there is uncertainty regarding the depth of infiltration or proximal extension . as kaposi noted more than a century ago , cutaneous horns can be removed by simple detachment and cauterization of the papillary base . stage one is establishing the diagnosis and next stage is a definitive treatment based on the histopathology . penile horn can hide either benign or malignant lesions . therefore , what is really important is not the cutaneous horn itself , but the subjacent disease . hence , it is justifiable to perform a local surgical excision for the histopathological diagnosis of its base . a wide local surgical excision is performed on the lesion in case of suspected malignancy to obtain the histopathological diagnosis . though various methods including electrosurgical excision , laser and cryosurgery , have been described as effective laser therapy with carbon dioxide or neodymium : yttrium aluminum garnet laser leaves lesser scarring with more cosmetic results . they are not preferred as they alter the histopathology of the lesion . in case of a benign lesion , excision of the horn would suffice . in case of verrucous carcinoma , wide local surgical excision should be followed up regularly . if the biopsy reveals squamous cell carcinoma , the treatment of choice is partial or complete penectomy with urethral diversion and perineal urethrostomy . the penile horn continues to fascinate the dermatologists and surgeons alike because of the morphological appearance and presentation . the penile horn is only a morphological entity and the true pathology masked by it .
cutaneous horn refers to unusually cohesive keratinized material and not a true pathologic diagnosis . 
 though cutaneous horn has been described at various sites , horn over the penis is very rare and represents the most unusual site . 
 the role of chronic irritation , phimosis , surgical trauma and radiotherapy have been implicated in penile horn formation . 
 penile horns present as elongated , keratinous , white or yellowish projections that range from a few millimeters to centimeters in size arising from the glans penis . 
 histopathology of the keratotic mass reveals nothing but keratin . 
 the underlying mass may vary from verruca vulgaris to squamous cell carcinoma . 
 the treatment is based on the pathology .