A rare interesting case of seborrheic keratosis of pinna

Seborrheic keratosis is a benign tumour of external ear originating from proliferative epithelial cells. Its most common site ranges from the retroauricular region to the helical rim. Diagnosis is made on the basis of clinical & histopathological examination. Here, we discuss the clinical presentation, differential diagnosis, pathological diagnosis and management of such a case.


INTRODUCTION
Seborrheic keratosis (seborrheic wart, senile wart) is usually small and multiple.It affects the neck and limbs.But large solitary lesions are very rare.Seborrheic keratosis should be included in the differential diagnosis of auricle lesions, but this fact has not been made adequately clear in the otolaryngologic literature [1].We will report a case in which a large solitary lesion affected the pinna.

Patient History
A 50-year-old patient from a village in Indore, for the last two years, has suffered from a blackish mass on the medial aspect of right pinna, which has gradually increased in size.There were no other associated symptoms, such as pain or itching.The patient recounted the excision of the mass 11 years earlier.The patient was diagnosed with diabetes and hypertension only after admission in hospital.

Local Examination
On local examination: Single firm blackish mass with a warty surface of 3 × 1.5 cm in size was present on the medial aspect of right pinna in the upper part.The mass was pedunculated and with a broad base.It was not tender.It was without any ulceration.And it did not bleed on touch [Figure 1].Other otorhinolaryngologic examination was within normal limits.A medical specialist treated the patient with subcutaneous regular insulin five units thrice a day and Amlodipine tablets five mg once a day for Diabetes (Random blood sugar-240mg/dl) and hypertension (Blood Pressure-180/110 mm Hg) respectively, both of which came under control after two days of treatment.

Management
Excisional biopsy under local anaesthesia (2% lignocaine with adrenalin) was done.Mass was sent for histopathological examination, report of which revealed seborrheic keratosis [Figure 2].

Histopathological Findings
Haematoxylin and Eosin stained sections showed basal cells of normal epidermis with variable amount of melanin pigment.The marked keratosis with keratin filled cyst and invagination of keratin in mass are suggestive of seborrheic keratosis or invaginating cyst [Figure 3].

Outcome
Due to good glycemic control, the post operative healing was adequate with the approximation of margins [Figure 4].Pt was followed in the immediate post operative period of 3 months.The course was uneventful.

DISCUSSION
The auricle is made up of many different types of tissue, each of which can give rise to one or more different types of tumor.The skin produces a wider variety of tumors than does any other organs.Clinically, benign tumors are usually characterized by slow or no growth.Microscopi-   cally, these tumors feature a well-organized cellular pattern [2].Ultraviolet light exposure, human papillomavirus infection, hereditary factors, action of oestrogen and other sex hormones are among those factors which have been suggested in the aetiology of this disease.Secondary malignant changes may occur but are extremely rare [3].Since it may be confused with malignant melanoma or squamous cell carcinoma, obtaining a specimen for histology is essential.Histologically this lesion can be divided into seven subtypes: acanthotic, hyperkeratotic, adenoidal or reticulated, clonal, irritated, inverted follicular keratosis, and melanoacanthoma variants.

Differential Diagnosis
Other lesions mimicking seborrheic keratosis in clinical presentation are:  Atheroma (sebaceous cyst, atheroma, steatoma, keratinous cyst) is a benign tumor which is mostly located in the back of the ear lobe.On clinical examination, it appears as a 5 -25 mm firm displaceable nodule and may show signs of secondary infection.Sometimes, a pinpoint depression at the surface of the cyst corresponds to the infundibulum of a preexisting hair follicle [3]. Actinic keratoses (solar keratoses or senile keratoses) is a UV light-induced lesion which is often located on the ear, especially on the helical rim.Its frequency increases with age and can progress to invasive squamous cell carcinoma in 20%.Its prevalence is higher in individuals with fair complexion.Mostly, a well-defined patch with a rough texture, 3 -8 mm in diameter, and a typically erythematous base is visible, accompanied by occasional hyperkeratosis.Signs of inflammation may occur [3]. Lentigomaligna (Hutchinson's freckle) is a slowgrowing, non-invasive melanoma in situ.The lesion begins as an unevenly pigmented and irregularly bordered, brown to black macule which slowly extends in the course of time [3].

Treatment
Although excisional surgery is not usually indicated for seborrheic keratosis, shave excision is an option when a histologic confirmation of free margins is desired [2].Finally, it has been reported that a sudden eruption of numerous pruritic seborrheic keratoses in an adult (Leser Trelat sign) is a sign of internal malignancy.This phenomenon is considered to be a paraneoplastic disorder [2].

Figure 4 .
Figure 4. Post-operative photograph showing pinna after excision of mass.