sebaceous cysts pictures
Sebaceous cysts pictures
Our skin is kept soft and oily due to the production of sebum from the sebaceous gland. The sebaceous gland will open to the hair follicle. However the opening of the sebaceous gland may be blocked which leads to the accumulation of the sebum in sebaceous gland which further leads to the formation of the sebaceous cyst. Generally the sebaceous cyst is filled with keratinise material and lined with epithelium. The sebaceous cyst tends to be slow growing and asymptomatic which can be caught while brushing the hair.
Besides obstruction of the pilosebaceous gland, sebaceous cyst is also associated with pathological remnant and insertion of the epidermal material into the dermis. Sebaceous cyst is rarely present before adolescent based on the fact sebaceous cyst is slow growing which means that it is more common in adult and middle age patient. It may present in adolescent due to the changes of the sebaceous gland during puberty. Sebaceous cyst may have present for several years before being noticed by the patient because of its slow growing nature.
Sebaceous cyst may also be associated with Gardner syndrome which consists of multiple colonic polyps, epidermoid cyst, fibroma and skull osteomas. Gardner syndrome is an autosomal dominant premalignant syndrome.
On examination, sebaceous cyst mostly present in the hair bearing region such as scalp, neck, shoulder, face, back . It may also present in any part of the body where sebaceous gland is present. Sebaceous cyst is rarely present on the palm of the hand or soles of the foot due to the lack of the sebaceous gland. Sebaceous cyst tends to appear as multiple, non - tender and slow growing lump.
The sebaceous cyst is spherical in shape and tense. On the scalp, with an underlying skull, the sebaceous cyst remains spherical in shape and bulging outward and stretching the overlying skin. The diameter of the sebaceous cyst is around few mm to 4 -5 cm. Sebaceous cyst has a smooth surface. The edge of the sebaceous cyst is well defined and easily felt. The edge of the sebaceous cyst is lying in the subcutaneous fat. The colour of the sebaceous cyst is similar to the colour of the skin. Sebaceous cyst is non tender in uncomplicated cases. However, infection or inflammation may lead to tenderness and pain. The inflamed sebaceous cyst may feel hot while normal sebaceous cyst has a normal temperature similar to the body temperature.
Sebaceous cyst is a solid and hard structure. It is so tense that make it difficult to elicit fluctuation. It is not transilluminated as sebaceous cyst contains sebum. On the scalp, the fluctuation may feel due to the resistance from the skull. Sebaceous cyst attaches and arises from the skin but sebaceous cyst lies in the subcutaneous tissue. The point of discharge of the sebaceous cyst is along the hair follicle. This point of fixation will be pulled inwards and form a visible punctum as the cyst grows. One and the half of the sebaceous cyst have visible punctum which is a useful diagnostic test and the attachments of the sebaceous cyst to the skin prevent the movement of the cyst independently. Sebaceous cyst is not associated with any enlargement of the lymph node.
Sebaceous cyst is originated from the epidermis of the infundibulum of the hair follicle. The sebaceous cyst will develop from the proliferation of the cyst of the epidermal cell within the dermis. The growth of the cyst is accelerated if the cyst is infected. The cyst via the visible punctum may also discharge its content which consists of a granular creamy caseating material with an unpleasant smell and later regresses and disappear.
Investigation such as skin biopsy and fine needle aspiration (FNA) is rarely performed as the diagnosis is made clinically.
The treatment may include conservative, surgical and medical treatments. The sebaceous cyst may be left alone if it is not distressing the patient. The next treatment may include a complete surgical excision of the entire cyst and its content intact as well as the skin punctum by removing an ellipse of the skin. Recurrence is common even though only a single lining of the cyst remain. Complete excision of the cyst is important. Local anaesthetic with adrenaline is used but in multiple large cysts general anaesthetic is required. The area of the sebaceous cyst also needs to shave to get a better access and view. Diathermy should always be available. Bleeding may occur during the excision of the lesion. The lesion is closed with mattress suture to aid haemostats . Mattress suture should be avoided in a region where cosmetic appearance is important. Medical treatment may include the prescription of the antibiotic. However, the definite treatment may include surgical excision.
Sebaceous cyst which is found on the scalp as a lump may get scratched while combing the hair. The scratch left behind may be infected which later develop into a cyst which become acutely painful and rapid growth. Besides infection, inflammation that happens at the same time may also lead to hot, tender and red sebaceous cyst. Sebaceous horn will form from the slow discharge from a wide punctum. If the infected cyst is neglected , the infection will spread to the wall of the cyst and surrounding tissue /skin producing the painful, boggy, discharging swelling known as Cock’s Peculiar Tumour.
Cock’s Peculiar Tumour is an opened, infected, granulating and edematous sebaceous cyst. Generally it is associated with an ulceration of the sebaceous cyst. The lesion is known as “angry, malignant and sores” and often mistaken for squamous cell carcinoma of the skin of the scalp. Granulation tissue that develops from the cyst lining will start to build up, accumulates and finally it will burst through the skin which gives an everted edge of the lesion. Any infection of the surrounding tissue and cyst wall will lead to odematous and tender areas. Enlargement of the regional lymph nodes is common.
Sebaceous horn is one of the complications of the sebaceous cyst. It is caused by the slow exudation of the sebum from a large central punctum of the sebaceous cyst. The sebum will be harder and later dry to form a sebaceous horn. It is rarely present due to the friction from the soap, water and clothes that remove the secretion as soon as it is discharged from the sebaceous cyst. Sebaceous horn will grow if the patient falls to wash over the skin of the sebaceous cyst. Wide opening of a cyst provides a great opportunity to develop a sebaceous horn. The sebaceous horn can be pulled off, or broken off from the cyst , as it doesn’t involve any intrinsic living system.
The prognosis of sebaceous cyst is excellent. The excision of the cyst is curative and most cases require no treatment at all.
Other variants of sebaceous cyst may include trichilemmal cyst and Pilar cyst or Pilar tumour. Most of the cysts are present on the scalp and arises from the infundibular portion of the hair follicle.
Trichilemmal cyst is an inherited disorder in an autosomal dominant pattern. Trichilemmal cyst is similar to sebaceous cyst. 90% of trichilemmal cysts present on the scalp and 70% of trichilemmal cysts are multiple. Pathologically trichilemmal cyst arises from the epithelium of the hair follicle. Trichilemmal cyst is lined with epithelial cells and doesn’t have any granular layer. Trichilemmal cyst is associated with calcification.
Pilar cyst/ Pilar tumour is due to the proliferation of the epithelium of the lining cyst. Pilar cyst is most prone to proliferate and ulcerated which leads to the formation of Peculiar Cock Tumour that resembles squamous cell carcinoma of the skin.
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