eMedicine - Poroma : Article by Timothy McCalmont, MD Page 1 of 8 Home | Specialties | Resource Centers | Learning Centers | CME | Contributor Recruitment March 16, 2007 nmlkji Articles nmlkj Images nmlkj CME Advanced Search Consumer Health Link to this site You are in: eMedicine Specialties > Dermatology > Benign Neoplasms Quick Find Author Information Rate this Article Introduction Poroma Clinical Email to a Colleague Differentials Last Updated: February 22, 2007 Workup Get CME/CE for article Treatment Synonyms and related keywords: poroma, apocrine poroma, juxtaepidermal poroma, juxta- Follow -up epidermal poroma, hidroacanthoma simplex, dermal duct tumor, adnexal neoplasm, adnexal tumor, Miscellaneous eccrine poroma, poromatosis, intraepidermal poroma, dermal poroma, poroid hidradenoma, Pictures acrospiroma Bibliography Click for related AUTHOR INFORMATION Section 1 of 10 images. Author Information Introduction Clinical Differentials Workup Treatment Follow -up Miscellaneous Pictures Bibliography Related Articles Author: Timothy McCalmont, MD , Director, UCSF Dermatopathology Service, Seborrheic Professor of Clinical Pathology and Dermatology, Departments of Pathology and Keratosis Dermatology, University of California at San Francisco Squamous Cell Timothy McCalmont, MD, is a member of the following medical societies: Alpha Carcinoma Omega Alpha , American Medical Association , American Society of Dermatopathology , California Medical Association , College of American Trichilemmoma Pathologists , and United States and Canadian Academy of Pathology Editor(s): Evan R Farmer, MD , Professor of Dermatology, Johns Hopkins University School of Medicine, Clinical Professor of Pathology, Virginia Continuing Commonwealth University School of Medicine; Consulting Staff, Department of Education Dermatology, Johns Hopkins Hospital, VCU Health Services; Richard P Vinson, CME available for MD , Assistant Clinical Professor, Department of Dermatology, Texas Tech this topic. Click University School of Medicine; Consulting Staff, Mountain View Dermatology, PA; here to take this CME. Jeffrey Meffert, MD , Assistant Clinical Professor of Dermatology, Medicine, University of Texas Health Science Center-San Antonio; Joel M Gelfand, MD, MSCE , Medical Director, Clinical Studies Unit, Assistant Professor, Department of Patient Education Dermatology, Associate Scholar, Center for Clinical Epidemiology and Click here Biostatistics, University of Pennsylvania; and Dirk M Elston, MD , Director, patient education. Department of Dermatology, Geisinger Medical Center Disclosure http://www.emedicine.com/derm/topic112.htm 16/3/2007 eMedicine - Poroma : Article by Timothy McCalmont, MD Page 2 of 8 INTRODUCTION Section 2 of 10 Author Information Introduction Clinical Differentials Workup Treatment Follow -up Miscellaneous Pictures Bibliography Background: A poroma is a benign adnexal neoplasm composed of epithelial cells that show tubular (usually distal ductal) differentiation. The malignant counterpart of a poroma is referred to as porocarcinoma. Poromas historically have been considered glandular adnexal neoplasms of eccrine lineage, and this view is so entrenched that the neoplasm is often referred to as eccrine poroma; however, recent analyses by many investigators suggest that poromas can be of either eccrine or apocrine lineage. Apocrine poromas are probably more common than those of eccrine lineage. Poromas belong to the spectrum of acrospiromas, along with nodular hidradenomas, clear cell hidradenomas, dermal duct tumors, and hidroacanthoma simplex. Pathophysiology: A poroma is a benign neoplasm that shows differentiation toward poroid (glandular ductal) cells. The malignant counterpart of poromas is porocarcinoma, which also shows poroid differentiation. Poromas occur only in the skin and are not known to affect any other tissues. Frequency: In the US: Precise prevalence figures have not been calculated for this benign neoplasm. Internationally: The worldwide prevalence is not thought to differ from that observed in the United States. Mortality/Morbidity: A poroma usually manifests as a solitary papule or nodule. Most lesions are asymptomatic, but minor pain can accompany some lesions. Rarely, the patient develops multiple poromas simultaneously, a phenomenon known as poromatosis. Multiple poromas may be of cosmetic concern and are sometimes disabling, especially if involvement of the sole is noted. Race: Poromas are not known to have racial or ethnic predilection. Sex: No sex predilection is known in the distribution of poromas. Males and females are equally affected. Age: Poromas can develop in persons of any age, but onset is typically in adulthood. CLINICAL Section 3 of 10 Author Information Introduction Clinical Differentials Workup Treatment Follow -up Miscellaneous Pictures Bibliography http://www.emedicine.com/derm/topic112.htm 16/3/2007 eMedicine - Poroma : Article by Timothy McCalmont, MD Page 3 of 8 History: Poromas typically are asymptomatic, slow-growing, or stable nodular lesions. Although most are asymptomatic, pain can be a presenting sign. Poromas are one of many types of benign adnexal neoplasms that can manifest secondarily within a nevus sebaceus. Physical: Poromas typically manifest as skin-colored papules or nodules smaller than 2 cm in diameter. Poromas may occasionally manifest as pigmented lesions. Protuberant lesions may exhibit surface erosion or ulceration. Rarely, a poroma manifests in association with nevus sebaceus as a secondary neoplasm. Causes: The specific causes of poromas are not known. In contrast to some adnexal neoplasms of follicular lineage, poroma development has no established familial predilection. DIFFERENTIALS Section 4 of 10 Author Information Introduction Clinical Differentials Workup Treatment Follow -up Miscellaneous Pictures Bibliography Seborrheic Keratosis Squamous Cell Carcinoma Trichilemmoma Other Problems to be Considered: Hidradenoma Acrospiroma Poroid hidradenoma WORKUP Section 5 of 10 Author Information Introduction Clinical Differentials Workup Treatment Follow -up Miscellaneous Pictures Bibliography Lab Studies: Blood laboratory testing is not necessary for the diagnosis of a poroma and is not appropriate in the evaluation of an afflicted patient. The diagnosis typically cannot be made based solely on clinical findings alone, although an experienced observer may recognize the entity. The diagnosis can be fully established after surgical excision with subsequent microscopical examination by an http://www.emedicine.com/derm/topic112.htm 16/3/2007 eMedicine - Poroma : Article by Timothy McCalmont, MD Page 4 of 8 appropriately trained and certified dermatopathologist. Imaging Studies: Imaging studies are not needed in the evaluation of this benign and typically superficial adnexal neoplasm. Other Tests: No other testing is applicable. Procedures: No procedures (other than simple excision) are applicable to this entity. Histologic Findings: Like all benign neoplasms, poromas typically show relatively sharp circumscription. Most tend to be small, although sizable tumors can be encountered. Poromas are composed of small cuboidal epithelial cells with monomorphous ovoid nuclei and inconspicuous nucleoli. The individual neoplastic cells have compact eosinophilic cytoplasm. Areas of ductal differentiation are manifested as tubules lined by a dense eosinophilic cuticle, and, sometimes, cytoplasmic vacuoles can also be seen as an indicator of luminal differentiation. Although poromas can usually be deemed benign based on circumscription and benign cytologic features, these lesions not uncommonly show small foci of necrosis en masse and a highly vascularized (granulation tissue–like) stroma, the combination of which can create concern for malignancy, especially in inexperienced observers. Poromas manifest several different variations. Intraepidermal poroma (historically known as hidroacanthoma simplex) represents a form of poroma in which nests of cells with tubular differentiation are confined to the surface epidermis, with no evidence of dermal involvement. This pattern of poromas can sometimes cause confusion with other entities that may exhibit an intraepidermal pattern of growth, including seborrheic keratosis and melanocytic neoplasms. Juxtaepidermal poroma refers to a pattern of poroma in which nests and thick cords of cells are in continuity with the epidermis but also involve the superficial dermis. The intervening stroma is highly vascularized, as described above. Dermal poroma (historically referred to as dermal duct tumor) represents a pattern of poroma confined wholly to the dermis. Some intradermal poromas have relatively little stroma, while others display the highly vascularized stroma that is typical of superficial poromas. Poromas belong to the family of tumors known as acrospiromas. These tumors all differentiate towards the acrosyringium. Other variants of acrospiroma include clear cell hidradenoma and nodular hidradenoma. Mixed patterns are common. Staging: Staging is not applicable to the evaluation of a benign neoplasm. TREATMENT Section 6 of 10 Author Information Introduction Clinical Differentials Workup Treatment Follow -up Miscellaneous Pictures Bibliography http://www.emedicine.com/derm/topic112.htm 16/3/2007 eMedicine - Poroma : Article by Timothy McCalmont, MD Page 5 of 8 Medical Care: Poromas do not require medical care; rather, they are diagnosed and treated surgically. Surgical Care: The diagnosis and treatment of poromas is typically performed