These authors detail the diagnosis and treatment of a 76-year-old patient who presented with a painless palpable mass along her dorsal first metatarsal shaft, a mass that had increased in size over the past few years.
Clear cell hidradenomas are relatively rare dermal sweat gland neoplasms believed to originate from the eccrine glands. These neoplasms are composed of two main cell types: a fusiform dense cell epidermoid and small amounts of glycogen, and a large “clear” cell, filled with glycogen.1 The neoplasm has both solid and cystic components, and cell types include epidermoid cells, which may transform into clear cells.1-3
Clear cell hidradenomas typically present as a solitary non-encapsulated dermal nodule, vary in coloration and have the potential for extension into the subcutaneous fat.1-3 Slightly more common in women with a ratio of 1.7 to 1, they most commonly occur on the head, upper limb and trunk, and mostly occur in middle age.1-4
A 76-year-old female with a past medical history of high cholesterol, pheochromocytoma and multiple lipoma and schwannoma resections presented over the course of three years for a painless palpable mass along her dorsal first metatarsal shaft. The patient stated the mass had been present since 2003. Upon initial presentation to the Foot and Ankle Institute at the Temple University School of Podiatric Medicine in 2008, the patient had a palpable, firm, superficial, nodular mass approximately 1.5 cm x 2.0 cm. The mass was non-fluctuant and reddish in color.
The patient stated that the mass had slowly increased in size over the past few years but was not painful. She denied any traumatic event to the area. The results of magnetic resonance imaging (MRI) favored a hemangioma or vascular malformation. Over the next two years, the patient refused excision of the mass. However, during this time, she had multiple soft tissue masses excised from different body regions. The soft tissue masses included a schwannoma from her posterior left calf. In 2011, the patient presented to the clinic. At this time, she stated that the previously painless mass was not only growing in size and changing in color, but was now causing her pain and discomfort in shoe gear and with ambulation. We obtained a second MRI prior to surgical excision.
The lower extremity physical examination showed palpable dorsalis pedis and posterior tibial pulses bilaterally, and normal capillary refill time. Sensation was normal to light touch, and there were 2/4 patellar and Achilles tendon reflexes. The patient had full muscle strength to all quadrants bilaterally. Abduction and valgus rotation of the hallux were present bilaterally but more severe on the left. She had decreased range of motion at the first metatarsophalangeal joints (MPJ) bilaterally but no pain with motion. Just medially and proximally to the left first MPJ, there was a palpable, superficial, non-fluctuant mass, which was immovable and purple. The mass measured 2.5 cm x 3.0 cm at that time.
A Closer Look At The MRI Results
The MRI examination obtained in 2008 of the left forefoot and midfoot occurred via a 1.5-Tesla scanner using a combination of axial and coronal T1 weighted spin-echo and axial, sagittal and coronal fat saturated T2-weighted spin-echo imaging sequences. In addition, physicians obtained fat saturated pre- and post-contract early and delayed axial images following uneventful administration of 13 cc of intravenous gadolinium. Physicians marked the site of the clinically palpable abnormality with a vitamin E capsule.
The MRI findings from 2008 revealed moderate to severe hallux valgus deformity and cystic changes to the first MPJ. Adjacent to the medial aspect of the first metatarsal neck and below the site of clinically palpable abnormality, there was a T1 hypointense and T2 hyperintense soft tissue mass with multiple internal septations. It measured 1.5 cm x 1.8 cm x 1.0 cm in AP, transverse and sagittal dimensions. There was early intense enhancement of the lesion with increased vascularity in the adjacent muscular fascial planes. The enhancement persisted on delayed scan and the findings were due to a likely acquired hemangioma or a venous malformation.
In 2011, there was a follow-up MRI of the left foot with the field of view extending from the ankle through the toes. Images include axial T1, axial T2 fat-saturated, coronal T1, coronal T2 fat-saturated, sagittal T1 and sagittal T2 fat-saturated sequences without intravenous or intra-articular gadolinium. The use of intravenous or intra-articular gadolinium could not occur due to an elevated glomerular filtration rate. Physicians placed a vitamin E marker at the region of a palpable mass.
These MRI findings include an increase in the size of the soft tissue mass at the medial aspect of the first metatarsal neck/shaft to 2.5 x 1.6 x 2.5 cm. The lesion was hypo-intense on T1 and hyper-intense on T2 with internal septations. The underlying cortex appeared normal and an effusion at the first MPJ was present. Again, these impressions favored hemangioma or vascular malformation. The physician discussed the findings with the patient and scheduled surgery for excision of the mass. We also discussed risks and possible complications.
Preoperative labs were within normal limits. At initial presentation, plain film radiographs showed a moderate to severe increase in the first intermetatarsal angle with cystic changes at the first metatarsal head. The mass was not radiographically visible initially and there was no cortical involvement appreciated. However, in 2011, the mass was clearly visible on plain film as a radiopaque soft tissue mass, just proximally and medially to the first MPJ, and dorsally to the first metatarsal shaft. Again, no cortical involvement was present.
What You Should Know About The Operative Course
Before excising the mass, the surgeon ensured supine positioning of the patient under monitored anesthesia care and administered a left posterior tibial block (20 mL of 0.5% Marcaine plain). Following standard surgical preparation and draping, the surgeon made an approximately 5 cm slightly curvilinear incision beginning at the dorsal medial aspect of the forefoot, and progressing just proximally to the first MPJ to encompass the mass. The surgeon extended the incision down to the subcutaneous tissue and ligated all vessels within the mass.
The mass appeared to have both vascular and connective tissue components. Using blunt dissection and an iris scissor, the surgeon freed the mass along the dermis. Upon dissection, the surgeon located a vascular supply to the mass plantarly and inferior to the extensor hallucis longus tendon. The surgeon tied off the vascular supply using a 3-0 Vicryl reel. The surgeon mobilized all surrounding structures from the surgical site and sent the specimen to pathology.
The surgeon then flushed the area with normal sterile saline and closed the wound sequentially with 2-0 Vicryl. The surgeon subsequently closed the skin with 4-0 nylon in a vertical mattress and simple suturing pattern, and applied a bandage. The patient left the hospital in stable condition and had no complications.
Pathologists examined two specimens: a 2.2 x 2 x 1.5 cm rubbery tan soft tissue nodule and a 2 x 1 cm, partially bisected brown skin surface. Microscopic examination revealed the mass was a clear cell hidradenoma that was incompletely excised.
The patient followed up in the office weekly. At the first postoperative visit, the incision site was intact with no evidence of dehiscence, infection or recurrence. She reported a decrease in pain to the area. During the second postoperative visit, suture removal occurred without incident. At the six-month follow-up, there was no recurrence of the mass and the patient had returned to wearing normal shoe gear without any difficulties.
Clear cell hidradenomas are generally asymptomatic, benign, slow-growing adnexal tumors. These neoplasms have both mixed solid and cystic components with the clear cells resulting from increased glycogen within the cytoplasm.1 Often, they are encapsulated and researchers have reported that they can be highly vascularized with vessels that may extend through the lobules of the neoplasm.1
There are many synonyms for clear cell hidradenomas. These synonyms include benign nodular hidradenoma, clear cell myoepithelioma, eccrine acrospiroma and eccrine sweat gland adenoma.1,5 These lesions are generally solid and cystic with a predilection toward the trunk, face and upper extremities. There is an approximately 3 percent incidence on the foot.1,2,6 Skin changes can occur. These changes may include thickening, ulceration, discharge, discoloration and tenderness. This tumor can occur at any age but it is most common in the fourth decade.1,2 However, there have been cases in patients as young as 3.5 years old.7
The treatment of choice is surgical excision as the rate of local recurrence is low.1-3,6,8 The potential for malignant change is low but studies have reported a malignancy rate of up to 6.7 percent.2,3,9
Due to the patient’s age and the fact that she had remained asymptomatic postoperatively, the surgeon decided not to perform a second surgical procedure to completely excise the remaining aspects of the mass. The patient continues regular follow-up and monitoring for recurrence of the mass.
Dr. Pontious is the Acting Chair of the Department of Podiatric Surgery and Assistant Dean of Clinical Education at Temple University School of Podiatric Medicine in Philadelphia.
Ms. Spiess is a fourth-year student at the Temple University School of Podiatric Medicine.
The authors thank Patrick Odgen, DO, a pathologist at Aria Hospital in Philadelphia.
1. Winkelmann RK, Wolff K. Solid-cystic hidradenoma of the skin. Arch Derm. 1968; 97(6):651-657.
2. Keasbey LE, Hadley GG. Clear-cell hidradenoma: report of three cases with widespread metastases. Cancer. 1954; 7(5):934-952.
3. Kersting DW, Helwig EB. Eccrine spiradenoma. Arch Derm. 1956; 73(3):199-227.
4. Revis P, Chyu J, Medenica M. Multiple eccrine spiradenoma: case report and review. J Cutan Pathol. 1988; 15(4):226-229.
5. Hashimoto K, DiBella RJ, Lever WF. Clear cell hidradenoma. Arch Derm. 1967; 96(1):18-38.
6. Will R, Coldiron B. Recurrent clear cell hidradeoma of the foot. Dermatologic Surgery. 2000; 27(7):685-6.
7. Faulhaber D, Worle B, Trautner B, Sander CA. Clear cell hidradenoma in a young girl. J Am Acad Dermatol. 2000; 42(4):693-5.
8. Collman DR, Blasko M, Alonzo J, Stess R. Clear cell hidradenoma of the ankle. J Foot Ankle Surg. 2007; 46(5):387-393.
9. Biedrzycki OJ, Rufford B, Wilcox M, Barton D, Jameson C. Malignant clear cell hidradenoma of the vulva: report of a unique case and review of the literature. Int J Gynecol Pathol. 2008; 27(1):142-6.