Hidrocystoma, or sudoriferous cyst, is an eyelid tumor originating from apocrine or eccrine sweat glands [1]. Presentation of this tumor in the orbit is very rare [2–6]. In 1973, Saunders reported a superficial 2 mm mass in the superior orbit of a newborn [2]. To date, six other cases have been reported in childhood with protean clinical findings; none of these presented at birth [2–6]. In this report, we describe a massive hidrocystoma at birth and review the related literature.

A full-term, female child with severe right eye proptosis was referred to our department in central Iran two hours after birth by Caesarian section. The baby had a birth weight of 3410 g and Apgar scores of 10 at one and five minutes. She was the second child of a 30-year old healthy mother who had undergone cesarean section for her first child as well. History of trauma and amniocentesis or similar procedures during the pregnancy period was negative. Neither the parents nor the older brother had a history of systemic or ocular problems.

Under ocular examination, she had severe right eye extrusion (Fig. 1) and a total corneal epithelial defect with a good red reflex. In palpation and transillumination, the right orbit seemed to include a cystic mass with fluid. Both pupils were reactive to light and no relative afferent pupillary defect was detectable. Anterior/posterior segment examination of the left eye was unremarkable. Based on the opinion of the consulting neonatologist regarding the general conditions of the case, general anesthesia and imaging was postponed to at least 72 h later. We admitted the case in our ward and performed cyst aspiration under ultrasonic guidance; 15 cc straw-colored fluid was obtained and proptosis resolved significantly. Then, blepharorrhaphy was performed due to eyelids eversion and severe conjunctival chemosis. Appropriate topical drugs were administered and the patient referred again to the neonatology department for further stabilization and evaluation. Orbital magnetic resonance imaging (MRI) showed a large retro-orbital mass being unilocular and extraconal with hypo-intensity in T1 and hyper-intensity in T2 (Fig. 2). The case underwent further daily ocular assessment until day 5; when proptosis began to worsen again (Fig. 3). On day 6, under general anesthesia, we aspirated the mass again and then, through a trans-conjunctival incision 3 mm beneath the tarsal plate, the mass was exposed. It was located in the inferior aspect of the orbit extending to its apex. Hemorrhagic vessels were cauterized and by blunt and sharp dissection, the mass was completely removed en-bloc. The wound was closed with vicryl 8.0. The diameter of the aspirated mass was about 4 cm (Fig. 4). In pathologic consultation, a cystic cavity lined by a layer of sweat duct like epithelium with apical snouts consistent with the diagnosis of apocrine hidrocystoma was reported (Fig. 5). The patient was followed for 3 months (Fig. 6) and had no significant complications.

Presentation of hidrocystoma in the orbit is extremely rare to the extent that its presentation at birth, as a micro-cyst had only been reported once [2]. The point that makes our case very impressive was its massive size, orbital location and presentation at birth.

From a pathological standpoint, hidrocystoma is a benign cyst originating from a sweat gland apocrine or eccrine in nature. The apical part of cellular cytoplasm is decapitated in the apocrine type (decapitation), while it remains intact in eccrine (exocytosis) glands [6]. This difference in secretion mechanisms gives the pathologic appearance of apical ‘snouts’ in the apocrine type.

In a review by Shield and Shield, the authors believe that differentiating between the main causes of orbital cysts without bone involvement in childhood may not be possible even with CT scan or MRI [7]. Differential diagnosis of what we presented in our neonate case may include: (i) surface epithelial lesions (e.g., conjunctival, respiratory epithelial, epidermal and dermoid cysts); (ii) teratomas; (iii) Neural cysts (e.g., cephalocele, congenital cystic eye); (iv) originating from adjacent structures (e.g., mucocele and dentigerous cysts); (v) parasitic cysts [7].

The picture of our case strongly argues against the well reputed theory of traumatic origin for orbital hidrocystoma by which it was postulated that this tumor may be the result of sweat gland cells implantation through the orbit [6]. Presentation of a large deep orbital hidrocystoma at birth in our case suggests the possible presence of choristomatous ectopic sweat gland cells in the orbit during embryogenesis.

Taken together, orbital hidrocystoma should be considered as a differential diagnosis of small/large; superficial/deep; congenial/post-traumatic; and, childhood/adult orbital cysts.