Background
Apocrine hidrocystomas are benign cystic proliferations of the apocrine secretory glands. Apocrine hidrocystomas most commonly appear as solitary, soft, dome-shaped, translucent papules or nodules and most frequently are located on the eyelids, especially the inner canthus. Apocrine hidrocystomas grow slowly and usually persist indefinitely.
Pathophysiology
The exact stimulus for the development of an apocrine hidrocystoma is unknown. Plausible causes of the closely related eccrine hidrocystoma include occlusion or blockage of the sweat duct apparatus, which results in the retention of sweat and a dilated cystic structure.
Epidemiology
US frequency
Apocrine hidrocystomas are relatively common in the United States.
Race
No predilection for race or geographic region is recognized for apocrine hidrocystomas.
Sex
No sex predilection is described for apocrine hidrocystomas.
Age
Apocrine hidrocystomas occur in adulthood, although in no particular age group.
Prognosis
Apocrine hidrocystomas grow gradually and persist indefinitely after attaining full size. They seldom recur after removal. Apocrine hidrocystomas are entirely benign. Cysts may annoy patients; however, symptoms usually are mild or absent. Vision usually is not affected.
Patient Education
Advise patients that apocrine hidrocystomas are benign.
History
Apocrine hidrocystomas usually are asymptomatic. No seasonal variation or familial tendencies have been identified. Apocrine hidrocystomas tend to appear during adulthood, grow slowly, and persist indefinitely.
Physical Examination
Apocrine hidrocystomas usually occur as solitary translucent papules or nodules. Consistency is fluctuant and cystic. Size varies from a few millimeters to approximately 1.5 cm. Tumors occasionally manifest as multiple lesions, especially when of the eccrine hidrocystoma type.[1, 2, 3, 4, 5]
Apocrine hidrocystomas often appear tense and shiny. The coloration varies from flesh-colored to blue or black (see image below).
View Image | Clinical example of apocrine hidrocystoma. |
Tumors have a predilection for the eyelid, particularly the inner canthus. Tumors may arise on other areas of the head, neck, and trunk.[6] Tumors also have been reported to occur on the penis, in the axillae, and in the anal region.
Lesion edges are not well delineated but blend gradually into adjacent skin. Walls, although translucent, are sufficiently thick that they seldom rupture spontaneously.
When incised, apocrine hidrocystomas collapse, and a thin, clear, brownish, or blackish fluid is released. The fluid color of an apocrine hidrocystoma does not result from the presence of melanin or hemosiderin but may result either from the Tyndall phenomenon or the presence of lipofuscin pigment.
Cysts are mobile with palpation and transilluminate.
Apocrine hidrocystomas are not affected by variation in temperature (unlike eccrine hidrocystomas).
Causes
Although the origin of apocrine hidrocystomas is not known entirely, they are believed to be adenomatous cystic proliferations of the apocrine glands.
Procedures
Diagnosis is made easily by biopsy.
Histologic Findings
The clinical appearance of a pea-sized cyst near the inner canthus of the eye, which contains a thin clear or pigmented fluid, suggests an apocrine hidrocystoma; however, histologic examination often is required to establish a specific and definitive diagnosis. Upon histologic examination, apocrine hidrocystomas show large unilocular or multilocular cystic spaces within the dermis (see the image below). Apocrine hidrocystomas are more likely to be multilocular than the closely related eccrine hidrocystoma.
View Image | Histology of apocrine hidrocystoma. Cystic spaces appear empty because sweat is removed during processing. Decapitation secretion often is seen in the.... |
The cyst wall is lined by apocrine-type secretory epithelium. The innermost layer of the wall is composed of a single (occasionally double) layer of cuboidal-to columnar-shaped cells. The nuclei of these cells are positioned basally. The outer layer of cells composing the cyst wall is formed by myoepithelial cells in which the long axes run parallel to the cyst wall.
Well-organized fibrous tissue surrounds the cyst. Papillary projections extend from the secretory layer into the cyst cavity, depicting decapitation secretion. The secretory cells contain periodic acid-Schiff–positive, diastase-resistant granules and occasionally contain pigment granules, which provide the brown color of the cystic fluid. This pigment is neither melanin nor hemosiderin. On electron microscopy, secretory cells have numerous, dense, lysosomal-type secretory granules typical of apocrine gland cells. They also have an increased number of annulate lamellae, which are unusual in normal apocrine cells.
Other Tests
On dermoscopy, aprocrine hidrocystomas often have a homogenous area that occupies the whole lesion and that may be accompanied by arborizing vessels. The color of the homogenous area can be skin colored, yellow, or blue.[7]
Surgical Care
Apocrine hidrocystomas can be incised and drained; however, electrosurgical destruction of the cyst wall often is recommended to prevent recurrence. Punch, scissors, or elliptical excision also can remove tumors. Multiple apocrine hidrocystomas can be treated with carbon dioxide laser vaporization.[8] Trichloroacetic acid has also been used.[9] One report suggests that multiple or recurrent hidrocystomas may be amendable to botulinum toxin A injection, with improvement.[10]
Author
Jesse M Olmedo, MD,
Disclosure: Nothing to disclose.
Coauthor(s)
Ronald P Rapini, MD, Professor and Chair, Department of Dermatology, The University of Texas MD Anderson Cancer Center; Distinguished Chernosky Professor and Chair of Dermatology, Professor of Pathology, University of Texas McGovern Medical School at Houston
Disclosure: Book royalties from Elsevier publishers.
Specialty Editors
Richard P Vinson, MD, Assistant Clinical Professor, Department of Dermatology, Texas Tech University Health Sciences Center, Paul L Foster School of Medicine; Consulting Staff, Mountain View Dermatology, PA
Disclosure: Nothing to disclose.
Rosalie Elenitsas, MD, Herman Beerman Professor of Dermatology, University of Pennsylvania School of Medicine; Director, Penn Cutaneous Pathology Services, Department of Dermatology, University of Pennsylvania Health System
Disclosure: Received royalty from Lippincott Williams Wilkins for textbook editor.
Chief Editor
William D James, MD, Paul R Gross Professor of Dermatology, Vice-Chairman, Residency Program Director, Department of Dermatology, University of Pennsylvania School of Medicine
Disclosure: Received income in an amount equal to or greater than $250 from: Elsevier; WebMD.
Additional Contributors
Carrie L Kovarik, MD, Assistant Professor of Dermatology, Dermatopathology, and Infectious Diseases, University of Pennsylvania School of Medicine
Disclosure: Nothing to disclose.
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