Slowly Growing, Ulcerating Nodule on the Posterior Ankle

Index: WOUNDS 2011;23(10):320–321

Presentation

  A 34-year-old Haitian man presented with a 1-year history of a gradually enlarging, ulcerating nodule on the right posterior ankle that bled after trauma. The patient denied any history of prior trauma at the site of the lesion and foreign travel. There were no HIV risk factors or personal or family history of skin cancer. The patient was otherwise healthy with no additional complaints. Physical examination revealed a 1.4 cm firm, hyperpigmented nodule with a yellow crateriform center on the right posterior ankle (Figure 1). A punch biopsy was performed (Figures 2, 3).   Histopathologic examination revealed a superficial and mid-dermal, multinodular proliferation of bland epithelioid cells with occasional foci of ductal differentiation embedded in a fibrotic stroma. Focal epidermal connection and mucinous metaplasia were noted. Immunohistochemical stains revealed diffuse positive staining of the lesional cells with cytokeratins (high and low) and variable positivity with epithelial membrane antigen (EMA), as well as negative S100P. Fungal, viral, and mycobacterial tissue cultures were negative and RPR was non-reactive. Bacterial tissue culture was positive for Prevotella oris and Staphylococcus aureus.   

Diagnosis

  Clear cell hidradenoma (nodular hidradenoma [NHA]).   

Discussion

  Also known as eccrine acrospiroma, clear-cell hidradenoma, solid-cystic hidradenoma and eccrine hidradenoma, NHA is commonly located on the head, neck, or trunk, but, as noted here, can present on the lower extremities. It typically appears in the fourth to the eighth decades of life as a solitary dermal nodule up to 2 cm in diameter that may be cystic or ulcerative with exudate.^1–4 On dermoscopy, NHA is associated with amorphous whitish areas, linear vessels, hairpin vessels, and reddish purple areas (corresponding to the cystic paces with hemorrhage evident histopathologically).¹   Prototypic histopathological features of NHA, seen in the present case, include a well-circumscribed dermal lobule, occasionally extending into the subcutis, containing solid and cystic areas with foci of ductal differentiation and “decapitation” secretion—the latter favoring the more recent view of NHA being of apocrine histogenesis.⁵ The solid portions of the tumor may demonstrate a biphasic cellular population of uniform polygonal clear cells with small dark eccentrically located nuclei and small round cells with eosinophilic cytoplasm and vesicular nuclei.⁶ The clear-cells are PAS-positive and diastase-digestible, indicating their glycogen content.² Immunohistochemical studies reveal positive staining of the lesional cells for pancytokeratin, CEA, CAM5,² and EMA.³ This case highlights a histologic variant of NHA, the mucinous hidradenoma, which has only been described in isolated case reports.^7,8   Though diagnosis of NHA can only be confirmed by a biopsy, some reports indicate that duplex ultrasonography can successfully reveal the cystic features of this entity prior to performing an invasive procedure.^5,9 In addition, MRI has been used for surgical planning in particularly large lesions located over the knee or the ankle.^3,4 Treatment with surgical excision results in extremely low recurrence rates.^3–5   

Treatment

  Because of the positive bacterial cultures, the patient was given cephalexin (500 mg) by mouth three times daily for 10 days. In this case, surgical excision was performed primarily to alleviate the patient’s symptoms. Patient has had no regrowth of the nodule at more than 16 months follow-up.   

Conclusion

  This case reminds clinicians of the entity of the nodular hidradenoma, a benign adnexal neoplasm, which does not threaten life but which can require surgical management for patient discomfort. A neoplasm should always be considered in the differential of any nonhealing ulcer, and, in such cases, a biopsy is absolutely essential to cinching the diagnosis.   

References

1. Yoshida Y, Nakashima K, Yamamoto O. Dermoscopic features of clear cell hidradenoma. Dermatology. 2008;217(3):250–251. 2. Schweitzer WJ, Goldin HM, Bronson DM, Brody PE. Ulcerated tumor on the scalp. Arch Dermatol. 1989;125(7):987–988. 3. Yu G, Goodloe S, D’Angelis CA, McGrath BE, Chen F. Giant clear cell hidradenoma of the knee. J Cutan Pathol. 2009;37(9):e37–41. 4. Collman DR, Blasko M, Alonzo J, Stess R. Clear cell hidradenoma of the ankle. J Foot Ankle Surg. 2007;46(5):387–393. 5. Faulhaber D, Wörle B, Trautner B, Sander CA. Clear cell hidradenoma in a young girl. J Am Acad Dermatol. 2000;42(4):693–695. 6. Ahmed TSS, Del Priore J, Seykora JT. Tumors of the Epidermal Appendages. In: Elder DE, ed. Lever’s Histopathology of the Skin. 10th ed. Philadelphia, PA: Lippincott Williams & Wilkins; 2009:852–900. 7. Goh SG, Carr R, Dayrit JF, Calonje E. Mucinous hidradenoma: a report of three cases. J Cutan Pathol. 2007;34(6):497–502. 8. Fitzgibbon JF, Googe PB. Mucinous differentiation in adnexal sweat gland tumors. J Cutan Pathol. 1996;23(3):259–263. 9. Cho KE, Son EJ, Kim JA, et al. Clear cell hidradenoma of the axilla: a case report with literature review. Korean J Radiol. 2010;11(4):490–492. The authors are from the Department of Dermatology, Boston University School of Medicine, Boston, Massachusetts. Address correspondence to: Jennifer Powers, MD Boston University School of Medicine Dept. of Dermatology 609 Albany St. Boston, MA 02118 617-638-5500 jennifer.powers@bmc.org