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Cysts of the skin comprise a broad and heterogeneous category. One of the most common cyst is an epidermal inclusion cyst, popularly and incorrectly referred to as a sebaceous cyst.


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Follicular Cyst in a Patient With Myotonic Dystrophy A Case of Cyst With Differentiation Toward Follicular Infundibulum, Isthmus, Inner Root Sheath, and Hair

Wataru Nishie, M.D.; Miyuki Iitoyo, M.D.; Hitoshi Miyazawa, M.D.

From the Department of Dermatology, Kin-I-kyo Sapporo Hospital, Sapporo, Japan.

Am J Dermatopathol 2001;23:521-524 Abstract quote

We report a case of follicular cyst, which developed in a patient with myotonic dystrophy (MyD).

Histopathologically, the cyst showed infundibular and trichilemmal keratinization, inner root sheath differentiation, aggregation of basaloid cells, and pilomatricoma-like changes in the pericystic connective tissue. These findings have been reported in follicular cysts with Gardner's syndrome (GS). Interestingly, pilomatricoma is known as one of the skin diseases associated with MyD, though there have been no reported cases of cyst formation with differentiation toward portions of hair follicle in a MyD patient.

In our case, we hypothesized that the cyst might be derived from embryonic follicular germinative cells or follicular stem cells under the genetic influence of the MyD gene, as observed in follicular cysts in patients with GS.


CUTANEOUS CILIATED CYST Arch Dermatol 1978;114:70-73
Suggested that these are heterotopia or vascular dissemination of Mullerian duct cells during early embryogenesis
  Am J Dermatopathol 2001;22:519-523
Positive for dynein, part of the units that junction as microtubule based molecular motors-supports Mullerian hypothesis

Detection of human papillomavirus 60 in epidermal cysts of nonpalmoplantar location.

Lee S, Lee W, Chung S, Kim D, Sohn M, Kim M, Kim J, Bae H, Kam S.

Am J Dermatopathol. 2003 Jun;25(3):243-7. Abstract quote

Human papillomavirus (HPV) types 57 and 60 are associated with epidermal cysts of palmoplantar location (PPECs). Recently, there was a report of HPV 60 in a wart located in a nonpalmoplantar area as a possible precursor of a nonpalmoplantar epidermal cyst (NPPEC). There has been no study that has examined the presence and frequency of HPV in ordinary NPPECs.

We reviewed 63 cases of epidermal cysts, including 59 NPPECs and 4 PPECs. After routine histopathologic review, polymerase chain reaction (PCR) of extracted DNA, sequencing of PCR products, and, finally, a homology search were undertaken. As a result, 9 of 63 (14.3%) cysts, including 6 of 59 NPPECs (10.2%), showed a positive reaction on PCR. By homology search after PCR, all were demonstrated as HPV 60.

For NPPECs, no variables, including some histopathologic features, are significantly related to the presence of HPV 60 in univariate or multivariate analysis (P > 0.05).

Milia en plaque: a case report and review of the literature.

Stefanidou MP, Panayotides JG, Tosca AD.

Department of Dermatology, Heraklion University General Hospital, Heraklion, Crete, Greece.

Dermatol Surg. 2002 Mar;28(3):291-5. Abstract quote  

BACKGROUND: Milia en plaque (MEP) is an unusual entity with a distinctive clinicohistologic appearance. Optimal treatment is unestablished, particularly for MEP located on difficult anatomic areas.

OBJECTIVE: To illustrate by a case report the clinical presentation and management of MEP.

METHODS: A 35-year-old woman with numerous tiny cysts within an slightly erythematous base in unilateral periorbital distribution is described. Histology revealed epidermal cysts arranged within the entire dermis.

RESULTS: Treatment with chemical exfoliating agents, manual extraction, and topical photodynamic therapy resulted in partial improvement.

CONCLUSION: Dermatologists should become familiar with this peculiar condition, being significantly rare possibly because of underreporting or misdiagnosis. New treatment procedures must be tried to achieve a successful cosmetic result with minimal risks.
Milia en plaque: a new site.

Alsaleh QA, Nanda A, Sharaf A, Al-Sabah H.

As'ad Al-Hamad Dermatology Center, Al-Sabah Hospital, Kuwait.

Int J Dermatol. 2000 Aug;39(8):614-5. Abstract quote  

A 35-year-old Kuwaiti field worker presented with a history of an asymptomatic, erythematous plaque on the right side of the nasal bridge. It soon extended to the malar area, being studded with multiple yellowish papules (Fig. 1). He denied any history of photosensitivity, drug intake, local trauma, topical applications, or ionizing radiations to that area.

Examination revealed an erythematous, 1.5 x 3 cm plaque on the right nasal fold, extending to the malar area, overlain by a group of tiny yellowish papules (15-20 in number). He also had a few discrete milia on the right cheek.

The histology (Fig. 2) revealed multiple keratin-filled cysts, surrounded by a dense lymphocytic infiltrate, findings consistent with milia; 0.05% tretinoin was prescribed twice daily for 1 month without improvement; minocycline, 100 mg daily, was then employed, and at 1 month of follow-up there was a significant decrease in erythema and milia count.

Milia en plaque.

Ergin S, Basak P, Sari A.

Department of Dermatology, Suleyman Demirel University Faculty of Medicine, Isparta, Turkey.
J Eur Acad Dermatol Venereol. 2000 Jan;14(1):47-9. Abstract quote  

Milia en plaque is a rarely reported entity which is usually appearing in the auricular region.

We describe a well-defined, U-shaped milia en plaque arising in the infraorbital area, and emphasize that it should be considered in the differential diagnosis of xanthalesma.
Milia en plaque of the eyelids in childhood: case report and review of the literature.

Bridges AG, Lucky AW, Haney G, Mutasim DF.

Department of Dermatology, University of Cincinnati Medical Center, Ohio, USA.

Pediatr Dermatol. 1998 Jul-Aug;15(4):282-4. Abstract quote  

Milia en plaque is a rare type of primary milia. Most of the reported cases have occurred around the ears in adults.

We report milia en plaque in a 10-year-old girl who presented with symmetrical erythematous plaques studded with milia on the eyelids. Histopathology revealed milia surrounded by a dense lymphocytic infiltrate.

Administration of minocycline and manual expression of the milia successfully treated this condition.
Milia en plaque associated with pseudoxanthoma elasticum.

Cho SH, Cho BK, Kim CW

Department of Dermatology, Catholic University of Korea, Seoul.

J Cutan Pathol. 1997 Jan;24(1):61-3. Abstract quote  

We report a woman with numerous milia occurring in a plaque-type distribution in the postauricular area, who has suffered from cutaneous pseudoxanthoma elasticum on both sides of the neck. Milia may arise primarily or may follow a number of dermatoses.

We believe this is a unique case because milia en plaque coexisting with pseudoxanthoma elasticum does not appear to have been reported previously.
'Milia en plaque' in the supraclavicular area.

Combemale P, Faisant M, Dupin M.

Department of Dermatology, Hopital d'Instruction des Armees Desgenettes, Lyon, France.

Dermatology. 1995;191(3):262-3 Abstract quote.  

'Milia en plaque' is an unusual skin disease. Up to date only 6 cases have been reported, and all of them were located in the retro-auricular area.

We report herein the first case of milia en plaque developed in the supraclavicular area.

The absence of a known aetiologic factor in contrast to the previously published cases suggests that the present case belongs to the group of primary milia.

Gastric mucosa in a bronchogenic cutaneous cyst in a child: case report and review of literature.

Vlodavsky E, Czernobilsky B, Bar Y, Lifschitz-Mercer B.

Patho-Lab Laboratories, Ness-Ziona, Israel.
Am J Dermatopathol. 2005 Apr;27(2):145-7. Abstract quote  

We report a case of cutaneous bronchogenic cyst, partially lined by gastric mucosa of antral type in a 9-year-old boy.

This is, to the best of our knowledge, the first report of gastric mucosa in bronchogenic cutaneous cyst in the literature.

Atrichia With Papular Lesions Electron Microscopic Observations of Cystic Lesions

Kazuo Nomura, M.D.; Isao Hashimoto, M.D.; Gen Takahashi, M.D.; Masaaki Ito, M.D. From the Department of Dermatology, Aomori Prefectural Central Hospital, Aomori (K.N.),

Departments of Dermatology (I.H.) and Anatomy (G.T.), Hirosaki University School of Medicine, Hirosaki, and Department of Dermatology, Niigata University School of Medicine, Niigata (M.I.), Japan.

Am J Dermatopathol 2001;23:227-231 Abstract quote

Atrichia with papular lesions is a rare inherited skin disorder characterized by congenital atrichia with numerous papules. We describe a 27-year-old woman with atrichia, who had numerous papules on her scalp, nape, and axillae.

Histologically, many keratinous cysts were seen in the middermis of a skin specimen from the nape. Electron microscopy showed that the developing keratinocytes in the walls of some cysts were rich in glycogen granules and had epidermoid keratinization with formation of keratohyaline granules and that laminated bodies were formed before keratinization. Langerhans cells were often seen in the walls of the cysts. In addition, a broad glassy vitreous layer surrounded the cyst wall.

From these findings, it was suggested that the cystic lesions might have originated from immature or incomplete hair follicles. In particular, the structure of the cyst wall corresponded well to infundibular and/or isthmal portions of the outer root sheath of the hair follicle.


Am J Dermatopathol 1994;16:76-79
J Cutan Pathol 1995;33-37
Histopathology 1995;26:467-469
Am J Dermatopathol 1997;19:93-96
Am J Dermatopathol 2001;22:519-523
Lower extremities of younger women (15-39 years)
One case in perineal region of a male

Occasional cases reported on scalp and shoulder
One case with evidence for estrogen and progesterone receptors

Dermal based multiloculated cyst with no definite capsule with a few small blunt papillae projected within the cyst

Single-layered columnar ciliated cells with cuboidal and columnar non-ciliated cells

Cutaneous ciliated cyst of the abdominal wall: a case report with a review of the literature and discussion of pathogenesis.

Fontaine DG, Lau H, Murray SK, Fraser RB, Wright Jr JR.

Departments of Pathology (D.G.F., S.K.M., R.B.F., J.R.W.), Surgery (H.L., J.R.W.), and Biomedical Engineering (J.R.W.), IWK Health Center and Queen Elizabeth II Health Center, Dalhousie University Faculty of Medicine, Halifax, Nova Scotia, Canada.

Am J Dermatopathol 2002 Feb;24(1):63-6 Abstract quote

A cutaneous ciliated cyst is a rare lesion typically found on the lower extremity of young girls shortly after puberty. Here, we report a case involving a previously unreported site (i.e., abdominal wall) in a 14-year-old girl.

We also describe immunohistochemical and ultrastructural findings, review and analyze the world literature, and offer insights as to the pathogenesis of this lesion.

Trichoblastic Infundibular Cyst.

From the *Department of Sensory Medicine, Division of Dermatology and Plastic Surgery, Akita University School of Medicine; and daggerSapporo Institute for Dermatopathology.


Am J Dermatopathol. 2006 Dec;28(6):507-509. Abstract quote

We report 4 cases of an infundibular cyst that histopathologically showed small papillary projections of follicular germinative cells emanating from the basal layer of the cyst wall. Some of these projections branched and formed a reticulated pattern. This cystic lesion is histopathologically distinctive.

We propose to designate it as a trichoblastic infundibular cyst because its lining resembles that of an infundibular cyst, yet it has cells that resemble those of the follicular germ in its wall.

Clinicopathologic features of epidermal cysts of the sole: comparison with traditional epidermal cysts and trichilemmal cysts*.

Shimizu Y, Sakita K, Arai E, Tsuchida T, Ogawa F, Ban S, Mitsuhashi T, Hirose T, Shimizu M.

Departments of Pathology and Dermatology, Saitama Medical School, Saitama, Japan.

J Cutan Pathol. 2005 Apr;32(4):280-5. Abstract quote  

Background: It has been described that the etiology of epidermal cysts on acral skin is different from that on non-acral skin; however, no papers have been published regarding the detailed histological differences between acral and non-acral epidermal cysts. In this study, we compared the clinicopathologic findings of epidermal cysts of the sole with those of traditional epidermal cysts and trichilemmal cysts.

Methods: The cases studied were 12 epidermal cysts of the sole, 35 traditional (non-acral) epidermal cysts, and 12 trichilemmal cysts. The age and sex of the patients and the site, size, and microscopic findings of the lesions were evaluated.The pattern of keratinization was specifically focused on the evaluation of microscopic findings.

Results: Microscopically, most of the epidermal cysts of the sole showed the presence of parakeratosis and focal lack of a granular layer at least at the upper portion of the cyst wall. The cyst content of the epidermal cysts of the sole was predominantly compact orthokeratotic material. These pathological findings could be explained by the pathogenesis of epidermal cysts of the sole, namely invagination of the surface epidermis.

Conclusion: Our study indicates that most cases of the epidermal cyst of the sole are considered to be a true traumatic epidermal inclusion cyst.

Median Raphe Cyst of the Penis A Report of Two Cases with Immunohistochemical Investigation

Mario Dini, M.D.; Gianna Baroni, B.Sc.; Maurizio Colafranceschi, M.D.

From the Department of Plastic Surgery (M.D.) and the Department of Human Pathology and Oncology (G.B., M.C.), University of Florence, Florence, Italy.

Am J Dermatopathol 2001;23:320-324 Abstract quote

Penile median raphe cysts are uncommon benign lesions occurring predominantly in the ventral aspect of the glans penis of young men. We observed two cases: those of a 67-year-old patient and a 22-year-old patient. The epithelial lining of the cysts was composed of pluristratified small cells that focally showed rows of columnar cells above the inner surface as well as a monolayered mucinous columnar epithelium. A columnar cell lining predominated in the younger patient. The cytokeratin (CK) immunostaining pattern of the two cysts (CK7+++, CK13+++, CK20, CAM 5.2+ ) supports the interpretation of a columnar mucinous epithelium undergoing immature urothelial metaplasia. Carcinoembryonic antigen immunostaining positivity of the columnar cells is probably related to the dysembryogenetic cloacal nature of the cysts. Neuroendocrine differentiation of sparse cells interspersed in the pluristratified epithelium was documented by immunohistochemical staining for chromogranin and synaptophysin. Cilia were not identified in the columnar cells by light microscopy or by antidynein immunohistochemistry.


Pigmented Epidermal Cysts

Tanuja Shet, M.D., D.N.B.; Sangeeta Desai, M.D.

From the Department of Pathology (T.S.), T. N. Medical College & B. Y. L. Nair Ch. Hospital, Mumbai Central, Mumbai; and Department of Pathology (S.D.), Tata Memorial Hospital, Parel, Mumbai, India.

Am J Dermatopathol 2001;23:477-481Abstract quote

There are few reports documenting the presence of melanin or melanocytes in epidermal cysts. One hundred and twenty five epidermal cysts from Indian patients were analyzed for the presence of melanin pigment and their sites were noted.

A Masson's Fontana stain and immunohistochemistry for S-100 protein and HMB 45 was performed for localization of melanin and melanocytes within the epidermal cysts. Seventy-nine (63%) of the epidermal cysts showed presence of melanin pigment or melanocytes to a variable extent. Melanin was not present in epidermal cysts occurring along lines of fusion of skin folds during embryonogenesis (e.g., ventral midline, inner canthus, nose, upper lip and in the distal most parts like leg and foot and also scrotum). Ten of the 79 epidermal cysts showed extensive accumulation of melanin pigment and infiltration with melanophages in the cyst wall. Four of these patients gave history of trauma and the follow-up was uneventful in two of them.

Pigmentation of epidermal cysts thus follows a definite anatomic pattern and is dependent on the natural skin color. Large amount of pigment accumulation within epidermal cysts occurs after cyst rupture and is not associated with hemochromatosis as was believed in the past.

Epithelial remnants of isthmus-catagen cysts.

Resnik KS, DiLeonardo M.

Institute for Dermatopathology, Conshohocken, Pennsylvania 19428, USA
Am J Dermatopathol. 2004 Jun;26(3):194-9. Abstract quote

The histopathologic diagnosis of isthmus-catagen cysts is typically rendered with ease at scanning magnification.

Episodically, diagnostic problems may arise when the outermost epithelial portion of the cyst wall separates from the remainder of the cyst.

If a histopathologist is unaware of this phenomenon, the findings may be misinterpreted.

Carcinoma arising in a proliferating trichilemmal cyst expresses fetal and trichilemmal hair phenotype.

Haas N, Audring H, Sterry W.

Department of Dermatology, Medical Faculty (Charite), Humboldt-University Berlin, Berlin, Germany.

Am J Dermatopathol 2002 Aug;24(4):340-4 Abstract quote

Carcinomas that arise in a proliferating trichilemmal cyst (PTC) have been described under a variety of names. Monoclonal antibodies (mAbs) indicating follicular differentiation have become available and were used here in two rare tumors with uncommon biologic behavior.

To further elucidate the histogenesis of carcinomas arising in a PTC, mAbs to hair follicle stem cells and to hair follicle differentiation-specific cytokeratins (mAbs to cytokeratin [CK] 7, CK8, CK18, and CK19 as well as mAbs to CD8/CK15 and CD34) were studied on paraffin-embedded sections of two cases of carcinoma arising in a PTC, one anaplastic carcinoma, and one poorly differentiated squamous cell carcinoma (SCC). For comparison, concurrent PTCs and trichilemmal cysts as well as four SCCs from controls were studied. The anaplastic carcinoma showed expression of CK7, indicating a fetal hair root phenotype, and expression of CD34, indicating trichilemmal differentiation.

In contrast, the poorly differentiated SCCs as well as the control SCCs stained negative for most of the mAbs applied. Expression of fetal and trichilemmal hair follicle phenotypes suggests differentiation from hair stem cells and might explain differences in biologic behavior.


Multiple follicular cysts, infundibular type with vellus hairs and solar elastosis of the ears: a new dermatoheliosis?

Morgan MB, Stevens GL, Somach S.

Department of Pathology, University of South Florida, FL; Haley Veteran's Hospital, Tampa, FL; Department of Dermatology, University of South Florida, FL; and Department of Dermatology, Cleveland Metro, Cleveland, OH, USA.

J Cutan Pathol 2003 Jan;30(1):29-31 Abstract quote

BACKGROUND: Vellus hair cyst is an uncommon developmental abnormality of the vellus follicle histologically defined as a stratified squamous epithelial-lined cyst containing one or more vellus hairs.

METHODS: Herein, we report three patients with a heretofore described clinicopathologic condition consisting of multiple contiguous cysts of the ear helices showing solar elastosis and multiple cysts containing vellus hairs, microscopically.

CONCLUSION: Given the anatomic location, history of excessive ultraviolet exposure and pathologic alterations, we surmise that this is a condition related to Favre-Racouchot syndrome, which is predisposed by excessive ultraviolet light exposure.


Cutaneous ciliated cyst
Am J Dermatopathol 1994;16:76-79
Positive for estrogen and progesterone receptors



Treatment of recurrent auricle pseudocyst with intralesional injection of minocycline: A report of two cases

Noritaka Oyama, MD, PhD
Morihiro Satoh, MD
Keiji Iwatsuki, MD, PhD
Fumio Kaneko, MD, PhD

Fukushima and Nihonmatsu, Japan

J Am Acad Dermatol 2001;45:554-6 Abstract quote

Pseudocyst of the auricle (PCA) is characterized by asymptomatic and fluctuant swelling of the external ear and frequent relapses despite various therapeutic approaches.

We describe two patients with recurrent PCA who were successfully treated with intralesional injection of 1 mg/mL of minocycline hydrochloride (minocycline), 2 or 3 times at 2-week intervals.

Intralesional injection of minocycline may be a new therapeutic choice for conservative management of PCA, especially in recurrent cases. The mechanisms of minocycline action that may have led to reduction of the cystic lesions are discussed.

Pseudocyst of the auricle: Diagnosis and management with a punch biopsy

2LT Amy Y. Paul, MSC, USA
CPT(P) Hon S. Pak, MC, USA
LTC Mark L. Welch, MC, USA
LCDR Charles B. Toner, MC, USN
CDR Joseph Yeager, MC, USN

Philadelphia, Pennsylvania, Washington, DC, and Bethesda, Maryland

J Am Acad Dermatol 2001;45:S230-2 Abstract quote

A case of pseudocyst of the ear diagnosed and treated with a punch biopsy is reported.

Pseudocyst of the ear is considered to be a benign, asymptomatic condition seen infrequently in clinical practice. Our patient is a 45-year-old white man who presented with a 5-month history of a painless nodule on his left auricle without any preceding history of trauma. Although many treatments have been reported, none appear satisfactory, and many surgical treatment modalities are cumbersome.

This is the first report, to our knowledge, of a case of a pseudocyst of the ear confirmed and treated with a 3-mm punch biopsy of the inferior border of the pseudocyst, followed by a pressure bolster.


Subungual myxoid cysts: Clinical manifestations and response to therapy

David de Berker, MRCP
Sophie Goettman, MD
Robert Baran, MD

Bristol, England, and Paris and Cannes, France


J Am Acad Dermatol 2002;46:394-8 Abstract quote

Background: Myxoid cysts located beneath the nail are very different from those within the nailfold and there is no established literature on their diagnosis and therapy.

Objective: Thirty-five cases of subungual myxoid cyst are described in which the diagnosis was confirmed by magnetic resonance imaging, surgical exploration, or both.

Methods: The clinical characteristics of all cases of subungual myxoid cysts confirmed in 3 specialist nail clinics are reported. Twenty cases were confirmed by magnetic resonance imaging. Histologic details were recorded in 4 cases.

Results: Thirty-four patients (22 female, 12 male) presented with a subungual tumor of the thumb (n = 25) or finger (n = 10). The 3 main clinical variables were color of the lunula, transverse nail curvature, and integrity of the nail. In 26 cases the lunula was discolored; it was red in 22 cases, blue in 3, and as part of a longitudinal leukonychia in one. Transverse curvature was increased in 29 cases and was normal in 5 cases; in one case the nail was destroyed. In 11 cases, the change in curvature led to lateral ingrowing. Surgery (n = 22), sclerosant (n = 1), and spontaneous discharge (n = 2) all resulted in resolution. Ten patients had no treatment.

Conclusion: This study describes 35 subungual myxoid cysts having characteristic features that allow clinical diagnosis. They respond to a range of treatments.

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