Slideshow
-
Slide
A 64-year-old man is referred for evaluation of a growth below his right knee. He states that he first noticed the lesion approximately 2 months ago and it has continued to enlarge. The site is tender and occasionally bleeds. He takes medications for adult-onset diabetes and hypertension and denies prior history of skin cancer. Examination reveals a 0.8 cm erythematous, firm nodule. No similar lesions are noted elsewhere.
Submit your diagnosis to see full explanation.
Biopsy of the lesion revealed a poroma, which is a benign adnexal neoplasm that arises from a sweat gland duct. First described in 1956, lesions were believed to originate exclusively from eccrine glands.1 Subsequently, poromas arising from apocrine glands have been documented.2 There is no sexual or racial predilection for the development of paromas. Lesions characteristically present as solitary, firm, dome-shaped papules or nodules that range in hue from flesh-toned to reddish blue. The majority of poromas occur in adults and arise most frequently on the palms and soles.
Dermoscopy of poroma is variable and often nonspecific.3 Definitive diagnosis is made by biopsy. The tumor is well circumscribed and contains non-palisading cuboidal keratinocytes and cytoplasm that stains positively with periodic acid–Schiff (PAS).4 Surgical excision is often recommended as a small percentage of lesions may transform into malignant porocarcinoma.5 Porocarcinoma is an aggressive neoplasm with high rates of recurrence after resection and the potential for metastatic spread to lymph nodes and vital organs.6
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. Goldman P, Pinkus H, Rogin JR. Eccrine poroma: tumors exhibiting features of the epidermal sweat duct unit. AMA Arch Derm. 1956;74(5):511-521.
2. Kamiya H, Oyama Z, Kitajima Y. “Apocrine” poroma: review of the literature and case report. J Cutan Pathol. 2001;28(2):101-104. doi:10.1034/j.1600-0560.2001.280207.x
3. Lai M, Muscianese M, Piana S, et al. Dermoscopy of cutaneous adnexal tumours: a systematic review of the literature. J Eur Acad Dermatol Venereol. 2022;36(9):1524-1540. doi:10.1111/jdv.18210
4. Ahmed jan N, Masood S. Poroma. In: StatPearls [Internet]. StatPearls Publishing; July 4 2022. https://www.ncbi.nlm.nih.gov/books/NBK560909/
5. Robson A, Greene J, Ansari N, et al. Eccrine porocarcioma (malignant eccrine poroma): a clinicopathologic study of 69 cases. Am J Surg Pathol. 2001;25:710-720. doi:10.1097/00000478-200106000-00002
6. Salih AM, Kakamad FH, Baba HO, et al. Porocarcinoma; presentation and management, a meta-analysis of 453 cases. Ann Med Surg (Lond). 2017;20:74-79. doi:10.1016/j.amsu.2017.06.027
QUESTION
