Multiple Asymptomatic Papules on the Back of the Right Side of the Chest.

A 43-year-old male presented with multiple asymptomatic papules on the back of the right side of the chest of 1 year duration. He was asymptomatic a year back then he developed small papules on the right side of the front of the chest initially and later on involved the front and back of the chest. No history was suggestive of leprosy and hyperlipidemias. Family history was negative for similar problem. Examination revealed multiple skin-colored to yellowish papules distributed on the front and back of the chest and shoulder region on the right side [Figure 1]. Also, there were multiple hyperpigmented macules on the right infrascapular region. There was no nerve thickening and no sensory deficit and there were no hypopigmented or anesthetic patches. Systemic examination did not reveal any abnormality. Routine investigations including complete blood picture, blood sugar, complete urine examination, blood urea, serum creatinine, liver function tests and serum lipid profile were normal. Fundus was normal. A slit skin smear for acid fast bacilli was negative. A punch biopsy from the representative lesion subjected to histopathological examination revealed a cyst with an intricately folded wall, lined by two to three layers of flattened squamous epithelium and the absence of the granular layer. Lobules of sebaceous glands were found embedded in cyst lining. The lumen was filled with amorphous eosinophilic material and multiple hair shafts [Figures 2-4].

Figure 1

(Original) Multiple skin-colored to yellowish papules on the back of chest and shoulder region on the right side

Figure 2

(Original) Histopathology of skin showing a cyst with an intricately folded wall lined by two to three layers of flattened squamous epithelium and the absence of granular layer. (H and E stain, ×100)

Figure 4

(Original) Histopathology of skin showing crenulated keratin (arrow). (H and E stain, ×400)

(Original) Histopathology of skin showing a lobule of sebaceous gland (short thick arrow) embedded in cyst lining with amorphous eosinophilic material (long thick arrow) and cluster of hair (long thin arrow) within the cavity of the cyst. (H and E stain, ×400)

Question

What is your diagnosis?

Answer

Steatocystoma multiplex

Discussion

Steatocystoma multiplex (SM) is a hamartomatous malformation of the pilosebaceous duct junction, was first described by Jamiesonin in 1873 and subsequently, Pringle coined the term in 1899.[1] It is an autosomal dominantly inherited disorder but sporadic cases have been reported in the literature.[2] The familial SM is associated with mutation in the keratin 17 gene and so far 14 mutations have been described in the literature.[34] It may be associated with other ectodermal dysplasias. The exact origin of the SM is not known. However, various theories have been put forward: Consequence of sebaceous retention cysts of nevoid nature could be hamartomas or could be a variety of dermoid cysts.[5] SM can present as localized, generalized, facial, acral, and suppurative types.[6] The solitary lesions are sporadic and they are known as steatocystoma simplex.

Adolescence or young adulthood is the usual age of onset suggesting a relationship with development of sebaceous glands and hormonal influence.[7] However, sporadic cases with presentation in elderly similar to the index case have also been reported. It presents with multiple skin-colored to yellowish smooth-surfaced papules and nodules predominantly distributed on trunk, front of neck, face and axillae, the areas normally rich in pilosebaceous units. Rarely SM may involve vulva and soles.[89] Usually asymptomatic but pain may be associated in suppurative form.[10] Both sexes are affected equally. However, higher prevalence among males has been reported in the literature.[11] It may be associated with acrokeratosis verruciformis, icthyosis, multiple keratacanthomas, hypertrophic lichen planus, pachynochia congenita, hypotrichosis, hydradenitis suppurativa and rheumatoid arthritis.[1213] However, there was no such association in the reported case. Nail changes like hypertrophic nail dystrophy have been reported in SM. However, such changes could not be seen in the index case. Ultrasonography shows well-demarcated, unechoic areas within the dermis and the subcutis. Histopathology of the lesion is confirmatory which shows an intricately folded wall, lined by two to three layers of flattened squamous epithelium and the absence of granular layer. Lobules of sebaceous glands are embedded in cyst lining. The lumen was filled with amorphous material. Immunohistochemistry study shows a calretinin-positive inner epithelial layer of the cyst.[14] However, immunohistochemical study could not be done in the index case. Histopathological differential diagnosis includes eruptive vellus hair cyst, epidermoid cyst, tricholemmal cyst and milium which can be differentiated from one another [Table 1].

Table 1

(Original) histopathological differential diagnosis of steatocystoma multiplex

Various treatment modalities have been tried which include isotretinoin, cryosurgery, surgical excision and laser treatment. Isotretinoin helps in decreasing the size of the lesions but does not eradicate the lesions.[15] Of all the treatments, surgical excision and laser therapy are known to produce least scarring.[1617]

Learning points

SM is a hamartomatous malformation of the pilosebaceous duct junction inherited as autosomal dominant disorder, due to mutation in the keratin 17 gene

Adulthood is the usual age of onset

It presents with multiple skin-colored to yellowish smooth-surfaced papules and nodules predominantly distributed on trunk, front of neck, face and axillae

Histopathology of the lesion is confirmatory, which shows an intricately folded wall lined by two to three layers of flattened squamous epithelium and the absence of the granular layer with lobules of sebaceous glands embedded in cyst lining

Treatment modalities include isotretinoin, cryosurgery, surgical excision and laser treatment.