Clinical Challenge: New Growth After Basal Cell Carcinoma

Dermal duct tumors belong to a group of benign skin adnexal neoplasms known as poromas, which are derived from cells of the terminal eccrine or apocrine sweat gland duct.1 The various types of poromas can be differentiated by location and histopathologic...

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Dermal duct tumors belong to a group of benign skin adnexal neoplasms known as poromas, which are derived from cells of the terminal eccrine or apocrine sweat gland duct.¹ The various types of poromas can be differentiated by location and histopathologic features.² Dermal duct tumors are also known as intradermal or dermal eccrine poromas. These neoplasms have no ethnic or racial predilection and most commonly affect older men.³ Long-term UV radiation exposure may play a role in the pathogenesis of dermal duct tumors.⁴

Dermal duct tumors are often misdiagnosed due to their nonspecific and variable clinical appearance.⁵ They often present as asymptomatic solitary dome-shaped papules, plaques, or nodules ranging in color from pink to erythematous.^1,6 Lesions are most commonly seen on acral, head, and neck surfaces; widespread lesions are referred to as poromatosis.² Differential diagnosis includes other sweat gland tumors such as porocarcinoma, basal cell carcinoma, hidradenoma, pyogenic granuloma, soft fibroma, hemangioma, pigmented nevus, and spiroadenoma.²

Dermoscopy may help rule out other pathologies, however, confirmatory diagnosis is based on biopsy.⁷ Histopathologic findings distinct to poromas are cuboidal keratinocytes with nonpalisading and monomor­phous ovoid nuclei associated with periodic acid–Schiff cytoplasm staining.⁵ Aggregates of these cells may show varying degrees of ductal or tubular formations.

Malignant transformation risk is minimal and superficial lesions may be removed by shaving or electrosurgical destruction.⁸ Simple excision suffices for deeper tumors.

Alexandra Stroia, BS, is a medical student at the Lake Erie College of Osteopathic Medicine. Stephen Schleicher, MD, is director of the DermDox Dermatology Centers, associate professor of medicine at Geisinger Commonwealth Medical College, and clinical instructor of dermatology at Arcadia University and Kings College.

References

1. Sawaya JL, Khachemoune A. Poroma: a review of eccrine, apocrine, and malignant forms. Int. J. Dermatol. 2014;53:1053-1061. doi:10.1111/ijd.12448
2. Lu R, Krathen RA, Markus RF. An unusual tumor of the forearm. Dermatol Online J. 2006;27(12):13.
3. Betti R, Bombonato C, Cerri A, Moneghini L, Menni S. Unusual sites for poromas are not very unusual: A survey of 101 cases. Clin Exp Dermatol. 2014;39(2):119-122. doi:10.1111/ced.12185
4. Puttick L, Ince P, Comaish JS. Three cases of eccrine porocarcinoma. Br J Dermatol. 1986;115(1):111-116. doi:10.1111/j.1365-2133.1986.tb06228.x
5. Ahmed Jan N, Masood S. Poroma. StatPearls [Internet]. Statpearls Publishing. Updated July 4, 2022. Accessed August 2. 2022. https://www.ncbi.nlm.nih.gov/books/NBK560909/
6. Shalom A, Schein O, Landi C, Maarghoob A, Carlos B, Scope A.  Dermoscopic findings in biopsy-proven poromas. Dermatol. Surg. 2012;38(7 Pt 1):1091–1096. doi:10.1111/j.1524-4725.2012.02407.x 
7. Miller AC, Adjei S, Temiz LA, Gill P, Siller A Jr, Tyring SK. Dermal duct tumor: a diagnostic dilemma. Dermatopathology (Basel). 2022;9(1):36-47. doi:10.3390/dermatopathology9010007
8. McCalmont TH, Pincus LB. Adnexal neoplasms. In: Bolognia J, Schaffer JV, Cerroni L, eds. Dermatology, Vol 2; 4th Ed. Elsevier; 2018:110.