Are You Confident of the Diagnosis?
What you should be alert for in the history
Hidrocystomas are common benign sweat gland lesions occurring on the face or scalp, most commonly affecting the eyelid. The typical clinical presentation suggestive of a hidrocystoma is that of an asymptomatic solitary, pea-sized, translucent or blue-black papule or cystic lesion on the head, especially on the eyelid of a middle-aged or elderly adult (Figure 1). However, the correct diagnosis is usually established by histopathologic examination of the lesion.
Characteristic findings on physical examination
Two clinical presentations of hidrocystomas have been described. The solitary or “Smith” type was originally described by Smith and Chernosky, and the multiple, so-called “Robinson” variant of hidrocystomas, reported by Robinson in 1893. The latter occurs most frequently in women who work in a hot and humid environment. Hidrocystomas can be of eccrine or apocrine origin.
On physical examination, hidrocystomas (eccrine or apocrine) appear as solitary or rarely multiple dome-shaped, smooth-surfaced papules or nodules (up to 1.5cm) on the face, neck and, rarely, the trunk. Interestingly, hidrocystomas rarely present in areas that are rich in apocrine glands. The clinical presentation of apocrine and eccrine hidrocystomas is similar and is very difficult to differentiate by either clinical or histologic characteristics. Slight differences in clinical presentation have been reported.
Apocrine hidrocystomas tend to be larger, with a diameter of 3 to 15mm and are most frequently located on the eyelids. The color of apocrine hidrocystomas varies from translucent to bluish black. The bluish color in apocrine hidrocystomas could be the result of Tyndall phenomenon and the presence of lipofuscin pigment.
Eccrine hidrocystomas are smaller, ranging from 1 to 6mm in diameter and flesh-colored. Eccrine hidrocystomas, either solitary or multiple, including Robinson-type multiple hidrocystomas, are most frequently located in the periorbital and malar area/cheeks. Rarely, they can involve the chest, shoulder, axilla, penis and anus (Table I).
|Clinical characteristics||Eccrine hidrocystoma||Apocrine hidrocystoma|
|Location||Face: periorbital, malar area||Face: eyelid (inner canthus)|
|Size||1 to 6mm||3 to 15mm|
|Color/consistency||Flesh-colored, translucent||Translucent, bluish-black|
|Number of lesions||Solitary or multiple (Robinson-type)||Solitary|
Expected results of diagnostic studies
Apocrine hidrocystomas are large, unilocular or multilocular cysts. The lining epithelium consists of inner secretory cells and an outer myoepithelial cell layer. Decapitation secretion (pinching off of the cytoplasm with intraluminal secretion) is a hallmark of apocrine hidrocystomas (Figure 2). The cystic space appears empty as sweat is removed during processing. PAS-positive granules and papillary projections can be seen.
The differential diagnosis of hidrocystomas includes the following entities: 1) cystic basal cell carcinoma (clinically presents as a bluish gray cystic lesion, which is very similar to hidrocystoma; however, it has a distinct histology); 2) melanocytic lesions (given the blue-black hue, hidrocystomas can be confused with melanocytic lesions, including benign nevi, blue nevi or even melanoma; they are differentiated by histology); 3) epidermal inclusion cysts (flesh-colored, firm, round papule or nodule with a central punctum anywhere on the body; histology is characteristic, showing a cyst containing laminated keratin and lined by stratified squamous epithelium); 4) milia (white-to-yellowish, firm, small, 1 to 2mm papule on facial skin, distinguished by histology showing a tiny epidermoid cyst); 5) syringoma (usually multiple, small, 1 to 2mm, yellow papules on or around the eyelids, histology showing small tadpole-appearing ducts is distinctive).
Eccrine hidrocystomas are more likely to be unilocular and the lining is composed of two layers of small cuboidal cells. In contrast to apocrine hidrocystomas, myoepithelial layer and secretory cells demonstrating decapitation secretion are not seen. S100 protein is expressed by the inner luminal layer in the solitary (but not multiple) eccrine hidrocystomas.
It is often difficult to differentiate apocrine from eccrine hidrocystomas, especially when the epithelium is flattened. In fact, it is now thought that most eccrine hidrocytsomas are of apocrine origin. Apocrine epithelium is recognized histologically by its bilayered architecture, apical snouts and periodic acid Schiff-positive decapitation secretion (Table II).
|Histologic characteristics||Eccrine hidrocystoma||Apocrine hidrocystoma|
|Cyst number||Unilocular||Often multilocular|
|Cyst lining||2 layers of cuboidal epithelium||1 to 2 layers: inner secretory and outer myoepithelial cells|
|S100 stain||Positive staining (solitary but not multiple, Robinson type)||No staining|
Who is at Risk for Developing this Disease?
A hot and humid environment has been suggested to play a role in the development of multiple eccrine hidrocystomas. This entity has been described in housewives who work in such an environment.
Multiple apocrine hidrocystomas are a feature of Schopf-Schultz-Passarge syndrome, a rare, autosomal recessive ectodermal dysplasia, characterized by hidrocystomas, palmoplantar hyperkeratosis, hypodontia, hypotrichosis and nail dystrophy.
Hidrocystomas have been described in patients with Goltz syndrome (focal dermal hypoplasia), a rare ectomesodermal dysplasia syndrome characterized by cutaneous, skeletal, dental, ocular, and soft-tissue defects.
Hidrocystomas have also been described in Graves disease, which has been hypothesized to be due to hyperhidrosis characteristic of patients with hyperthyroidism.
What is the Cause of the Disease?
Laboratory or imaging studies have little value as the diagnosis relies on histology. The etiology of hidrocystomas in general is unknown. A hot and humid environment has been implicated in the etiology of some cases of eccrine hidrocystomas, especially in the multiple, Robinson-type hidrocystomas, where occlusion or blockage of the sweat duct and resultant retention of perspiration may play a role in the pathogenesis. Apocrine hidrocystomas are not affected by variations in temperature.
Systemic Implications and Complications
Hidrocystomas are benign, asymptomatic lesions and in most cases, they are not associated with systemic disease or complication.
Rarely, hidrocytsomas are associated with inherited disorders, such as Schopf-Schultz-Passarge syndrome and focal dermal hypoplasia (Goltz syndrome). Hidrocystomas have rarely been reported to be associated with Graves disease. In these cases, hidrocystomas resolve upon treatment of hyperthyroidism.
Table III. Treatment options for hydrocystoma
|Surgical Procedures||Medical Treatment|
|Needle puncture||Topical atropine cream|
|Excision||Topical scopolamine cream|
|Electrosurgical destruction||Trichloroacetic acid|
|Incision and drainage||Botulinum toxin A injection|
Optimal Therapeutic Approach for this Disease
In the case of solitary hidrocystomas, needle puncture is the simplest treatment modality. When apocrine hidrocystomas are incised, a colorless or brownish fluid is released. This modality, however, sometimes provides only temporary improvement. Most solitary hidrocystomas are easily treated with surgical excision of the lesion. Another reasonable treatment alternative is incision and drainage, although this approach can be associated with a high rate of recurrence after 6 weeks. Therefore, some authors recommend electrosurgical destruction of the cyst wall as the preferred treatment to prevent recurrence.
In the clinical setting of multiple hidrocystomas, if the history suggests worsening in hot and humid environment, avoidance of such conditions is warranted as it may result in resolution of the lesions.
Electrodessication can be used in the management of multiple hidrocystomas, if individual lesions are less than 1cm in diameter.
Some success in the management of multiple hidrocystomas has been reported with carbon dioxide laser vaporization, pulsed-dye laser, 1450nm diode laser and 595nm long-pulsed laser treatments.
Additional therapies reported with variable success in hidrocystomas are trichloroacetic acid. After local anesthesia first, the cyst content is aspirated with an empty syringe and then refilled with a second syringe containing 0.2mL of 20% TCA. The TCA is left in the cyst for up to 1 minute, aspirated and washed with distilled water to remove any residual TCA.
Treatment-resistant and recurrent multiple hidrocystomas can be treated with intradermal injections of low-dose botulinum toxin type A (BTX-A). Perilesional injections of 1 to 3 units of BTX-A into the superficial dermis are performed, spaced every 4 to 5mm (up to a total of 50U, dissolved in 2.5mL of normal saline). Complete resolution of the cysts can be achieved; however, repeated treatments are often necessary. As increased sweat production may aggravate multiple eccrine hidrocystomas, the mechanism of action of BTX-A is likely related to the reduction in eccrine sweat gland production.
Anticholinergic creams, such as topical 1% atropine ointment and scopolamine cream have been used with variable success, and such treatments are limited by the anticholinergic side effects of these medications.
Explain to the patient that this is a benign, asymptomatic lesion, which grows slowly until it reaches its full size. It rarely recurs after removal.
Unusual Clinical Scenarios to Consider in Patient Management
In very rare instances, hidrocystomas can be associated with inherited disorders, such as Schopf-Schultz-Passarge syndrome and focal dermal hypoplasia (Golz syndrome). The management of such cases is similar to nonsyndromic hidrocystomas.
When hidrocystomas are associated with Graves disorder, the treatment of hyperthyroidism may result in improvement of the lesions.
What is the Evidence?
Smith, JD, Chernosky, ME. “Hidrocystomas”. Arch Dermatol. vol. 108. 1973. pp. 676-9. (This is the first description of solitary hidrocystomas in the literature.)
Sarabi, K, Khachemoune, A. “Hidrocystomas–a brief review”. Med Gen Med. vol. 8. 2006. pp. 57(This is an excellent review of the literature on hidrocystomas. The authors discuss the characteristic histologic and clinical features, differential diagnosis and the effectiveness of experimental treatment modalities.)
Malhotra, R, Bhawan, J. “The nature of pigment in pigmented apocrine hidrocystoma”. J Cutan Pathol. vol. 12. 1985. pp. 106-9. (This report discusses the reason for the frequently clinically bluish appearance of apocrine hidrocystomas. The authors present a case of pigmented apocrine hidrocystoma with evidence of melanin as the underlying mechanism of the pigmentation and suggest that the Tyndall effect could be the explanation of the pigmentation seen clinically in most cases of apocrine hidrocystomas.)
Elder, D, Elenitsas, R. “Atlas and synopsis of lever's histopathology of the skin”. 2010. pp. 449-450. (Description of the characteristic histopathologic features of hidrocystomas.)
Alfadley, A, Al Aboud, K, Tulba, A, Mourad, MM. “Multiple eccrine hidrocystomas of the face”. Int J Dermatol. vol. 40. 2001. pp. 125-9. (This is a case series of multiple eccrine hidrocystomas of the face describing the characteristic clinical and histologic features of five women presenting with this entity. All cases were middle-aged women with multiple asymptomatic, skin-colored to bluish, papulonodular skin lesions in a centrofacial distribution. Histopathologically, all cases showed unilocular cysts in the dermis lined by two layers of cuboidal cells.)
Castori, M, Ruggieri, S, Giannetti, L, Annessi, G, Zambruno, G. “Schopf-Schulz-Passarge syndrome: further delineation of the phenotype and genetic considerations”. Acta Derm Venereol. vol. 88. 2008. pp. 607-12. (This is a case report of two patients with Schöpf-Schulz-Passarge syndrome, an ectodermal dysplasia, characterized by palmo-plantar keratoderma, hypodontia, hypotrichosis and nail dystrophy. Multiple eyelid apocrine hidrocystomas are described in all of the cases and are the hallmark of this condition.)
Buchner, SA, Itin, P. “Focal dermal hypoplasia syndrome in a male patient. Report of a case and histologic and immunohistochemical studies”. Arch Dermatol. 1992. pp. 1078-82. (The authors present a patient with Goltz syndrome (focal dermal hypoplasia), a rare ectomesodermal dysplasia syndrome with characteristic cutaneous, skeletal, dental, ocular, and soft-tissue defects. The patient was also noted to have apocrine hidrocystoma of eyelids.)
Nagai, Y, Ishikawa, O, Miyachi, Y. “Multiple eccrine hidrocystomas associated with Graves’ disease”. J Dermatol. vol. 23. 1996. pp. 652-4. (This is a case report of a 24-year-old woman who presented with hidrocystomas in the periorbital and malar areas, hyperhidrosis, finger tremor, exophthalmos and goiter. She was subsequently diagnosed with Graves disease. Following treatment for Graves disease, her skin lesions resolved completely.)
del Pozo, J, Garcia-Silva, J, Pena-Penabad, C, Fonseca, E. “Multiple apocrine hidrocystomas: treatment with carbon dioxide laser vaporization”. J Dermatolog Treat. vol. 12. 2001. pp. 97-100. (In this paper, the authors describe the efficacy and good cosmetic outcome with the use of carbon dioxide laser vaporization in the treatment of multiple apocrine hidrocystomas.)
Correia, O, Duarte, AF, Barros, AM, Rocha, N. “Multiple eccrine hidrocystomas–from diagnosis to treatment: the role of dermatoscopy and botulinum toxin”. Dermatology. vol. 219. 2009. pp. 77-9. (In this paper, the authors describe the dermoscopic features and the efficacy of botulinum toxin A injections in the treatment of multiple apocrine hidrocystomas.)
Armstrong, DK, Walsh, MY, Corbett, JR. “Multiple facial eccrine hidrocystomas: effective topical therapy with atropine”. Br J Dermatol. vol. 139. 1998. pp. 558-9. (This is a case report of a patient with a history of worsening multiple facial hidrocystomas during excessive episodes of sweating. The authors report resolution of the hidrocystomas within 1 week of application of 1% topical atropine.)
Dailey, RA, Saulny, SM, Tower, RN. “Treatment of multiple apocrine hidrocystomas with trichloroacetic acid”. Ophthal Plast Reconstr Surg. vol. 21. 2005. pp. 148-50. (The authors describe the efficacy and technique of trichloroacetic acid injections in the treatment of multiple apocrine hidrocystomas.)
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