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 Table of Contents  
CASE REPORT
Year : 2017  |  Volume : 9  |  Issue : 3  |  Page : 119-121  

Follicular hybrid cyst with rare juxtaposition of epidermal cyst and steatocystoma


Department of Pathology, Sonoscan Healthcare, Malda, West Bengal, India

Date of Web Publication21-Aug-2017

Correspondence Address:
Krishnendu Mondal
C/o.Barendra Nath Mondal, Fularhat, P.O. and P.S. Sonarpur, South 24 Parganas, Kolkata - 700 150, West Bengal
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/ijt.ijt_21_17

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   Abstract 

Any cutaneous cyst differentiating toward two or more pilosebaceous components is known as follicular hybrid cyst (FHC). A combination of epidermal and trichilemmal cyst is its most frequent example. Other combinations of pilosebaceous derivatives occur uncommonly as well. The histogenesis of this condition has been controversial. In this latest report, we describe an unusual FHC from the earlobe of a 19-year-old male, which expressed the cohabitation of epidermal cyst and steatocystoma. A sharp transition was noted between the two kinds of epithelial components.

Keywords: Earlobe, epidermal cyst, follicular hybrid cyst, pilosebaceous follicle, steatocystoma


How to cite this article:
Mondal K, Mandal R. Follicular hybrid cyst with rare juxtaposition of epidermal cyst and steatocystoma. Int J Trichol 2017;9:119-21

How to cite this URL:
Mondal K, Mandal R. Follicular hybrid cyst with rare juxtaposition of epidermal cyst and steatocystoma. Int J Trichol [serial online] 2017 [cited 2022 Jan 21];9:119-21. Available from: https://www.ijtrichology.com/text.asp?2017/9/3/119/213338


   Introduction Top


Cutaneous cysts usually develop as retention cysts from any of the three segments of a hair follicle, i.e., infundibulum, isthmus, and inferior portion. Occasionally, it exhibits two or more different epithelial derivatives from the pilosebaceous unit. Such cysts are known as follicular hybrid cysts (FHCs).[1] They commonly express conjugal epidermal/infundibular and trichilemmal differentiation. However, other less frequent combinations exist as well.[2] In this report, we describe a FHC located over the earlobe with features of epidermal cyst and steatocystoma.


   Case Report Top


At the surgical outpatient department, a 19-year-old boy presented with an insidious-onset, skin-colored firm subcutaneous nodule on the right earlobe for the past 2 years. It measured around 2 cm in diameter. A tiny surface punctum was also identified at its tip [Figure 1]. The lesion was enucleated under local anesthesia. Grossly, it appeared as well-encapsulated unilocular cyst beneath the epidermis. Its cavity contained oily cheesy substances. Under microscope, the cyst wall comprised two distinct patterns of pilosebaceous epithelium with an abrupt transition between them. Superficially, toward the epidermis, there was a stratified keratinizing squamous epithelium, reminiscent of the follicular infundibulum. It showed normal physiological maturation through stratum basale-spinosum-granulosum up to stratum corneum. Immediately juxtaposed to it, there was a multilayered epithelium characteristic of steatocystoma. This epithelium comprised three-to-four-cell layer thick strata of swollen sebaceous cells, which bore abundant foamy cytoplasm resembling as a delicate network. Toward the surface, these sebaceous cells were occasionally replaced by clear fat vacuoles, i.e., reminiscent of its disintegrated remnant in the process of holocrine secretion. Luminal to these cells, there was a discontinuous layer of stratified squamous epithelium without any intermediate granular layer. Focally, some multinucleate large polygonal cells with abundant dense granular cytoplasm were also present [Figure 2]. The cyst cavity contained keratin debris only. The ultimate diagnosis was rendered as “FHC with the components of epidermal cyst and steatocystoma.”
Figure 1: Clinically, skin-colored nodule at the lower pole of pinna with a tiny (arrow) surface punctum

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Figure 2: Histopathologically, hybrid cyst comprising steatocystoma (right half) and epidermal cyst (left half) with an abrupt transition (arrow) in between. Note the intermittent presence of stratified squamous cells over the sebaceous epithelium (a) (H and E stain, ×40). Steatocystoma component characterized by multilayered sebaceous epithelium (b) with occasional presence of multinucleate giant cells (c) (H and E stain, ×400). Epidermal cyst featuring stratified squamous epithelium with intermediate stratum granulosum and laminated keratinization (d) (H and E stain, ×400)

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   Discussion Top


Pilosebaceous cysts include epidermal cysts, originating from the follicular infundibulum; trichilemmal cysts, from the isthmus; vellus hair cysts, from the developmental defect in the vellus hair follicles; and steatocystoma, from the sebaceous duct. Some authors also encompass pilomatrixoma and apocrine hidrocystoma within this spectrum. The term “FHC” is coined for lesions featuring two or more of these cystic components.[2] The pathogenesis of FHC has been debated as collision of multiple pilosebaceous cysts, or multidimensional differentiation of pluripotent follicular stem cells, or else metaplastic conversion of one component to the other.[1],[3] The discussed FHC comprised epidermal cyst and steatocystoma, which originate from two contiguous pilosebaceous segments. Hence, the pathogenesis of this cyst is explainable by all those three pathomechanisms. Consequently, recognition of the appropriate histogenetic pathway involved in FHC requires further case studies including their scrutinizing molecular and genetic evaluation.

The maiden case of FHC was demonstrated by McGavran and Binnington,[4] which exhibited infundibular and trichilemmal differentiation. In subsequent years, the same combination turned into most frequent composition of FHCs.[3] Contradictorily, Kim et al.[5] reported seven FHCs of epidermal cysts combining with pilomatrixomas. Rarely, cysts featuring trichilemmal with pilomatrical, pilomatrical with steatocystoma, epidermal with apocrine, and vellus hair cyst with steatocystoma or epidermal or trichilemmal derivatives have also been described.[2] The coexistence of epidermal cyst with steatocystoma, like the present case, has been reported only once before. In that presentation, both the examined FHCs contained vellus hair cyst as the third component.[6] However, the currently described cyst exclusively consisted of epidermal cyst and steatocystoma.

FHCs mostly arise in the face and scalp.[2],[3] The present case only slightly differs for being located on the pinna. Histologically, there is usually a sharp transition between the epithelial components of FHCs.[2],[5] However, few exceptional cases of combined epidermal cyst and pilomatrixoma featured a transformation zone at the interface.[3],[7] Microscopically, the steatocystoma comprises 2–4 layers of swollen sebaceous cells with unapparent intercellular bridges. Keratinized squamous cells without interposing stratum granulosum cover its surface. Large polygonal cells with ample amount of granular cytoplasm, of macrophage/monocyte lineage, occasionally form part of the cyst lining.[2] Similarly, in the discussed case, there was a sharp demarcation between its epithelial components. The signature histomorphology of both compositions was maintained. At places, there was a relative predominance of sebaceous cells as well as the presence of multinucleate giant cells within the steatocystoma element. However, it did not pose any diagnostic difficulty at all.


   Conclusion Top


FHCs are rare cutaneous appendageal pathology. Therein, conjugal juxtaposition of epidermal cyst and steatocystoma is furthermore rarer. With the detection of newer epithelial combinations, the pathomechanism of FHCs remains complicated. More implicit studies on the topic might be useful to amend a common summated pathogenesis for all the cutaneous cysts and tumors.

Acknowledgment

We acknowledge the Department of Surgery for helping us with the clinical picture of the patient.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
   References Top

1.
Hwang SW, Cho KJ, Oh DJ, Lee D, Kim JW, Park SW. Two pilosebaceous cysts with apocrine hidrocystoma in one biopsy site: A spectrum of the same disease process? Ann Dermatol 2008;20:11-3.  Back to cited text no. 1
    
2.
Weedon D. Cysts, sinuses and pits. In: Davie B, editor. Weedon's Skin Pathology. 3rd ed. London: Churchill Livingstone, Elsevier; 2010. p. 442-57.  Back to cited text no. 2
    
3.
Lee KY, Kwon YS, Roh MR, Chung KY. A case of a follicular hybrid cyst. Ann Dermatol 2007;19:153-6.  Back to cited text no. 3
    
4.
McGavran MH, Binnington B. Keratinous cysts of the skin. Identification and differentiation of pilar cysts from epidermal cysts. Arch Dermatol 1966;94:499-508.  Back to cited text no. 4
    
5.
Kim MS, Lee JH, Son SJ. Hybrid cysts: A clinicopathological study of seven cases. Australas J Dermatol 2012;53:49-51.  Back to cited text no. 5
    
6.
Ahn SK, Chung J, Lee WS, Lee SH, Choi EH. Hybrid cysts showing alternate combination of eruptive vellus hair cyst, steatocystoma multiplex, and epidermoid cyst, and an association among the three conditions. Am J Dermatopathol 1996;18:645-9.  Back to cited text no. 6
    
7.
Sanusi T, Qu X, Li Y, Zhang J, Wang M, Zhao Y, et al. Follicular hybrid cyst: A combination of bullous pilomatricoma and epidermoid cyst. Int J Clin Exp Pathol 2013;6:3019-22.  Back to cited text no. 7
    


    Figures

  [Figure 1], [Figure 2]


This article has been cited by
1 Trichilemmal Cysts With Divergent Ductal Differentiation: A Series of 4 Cases
Irfan Khan, Garth R. Fraga, Hongyan Dai
The American Journal of Dermatopathology. 2021; 43(7): 493
[Pubmed] | [DOI]



 

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