Otology & Neurotology 36:e142Ye143 Ó 2015, Otology & Neurotology, Inc.
Temporal Bone Histopathology Case of the Month
Eccrine Poroma of the External Auditory Canal *Steven Zuniga, †Jasvir S. Khurana, and *Pamela C. Roehm *Departments of Otolaryngology and ÞPathology, Temple University School of Medicine, Philadelphia, Pennsylvania, U.S.A.
for less than 1% of primary cutaneous lesions (1). Up to 30% of these lesions are found on the head and neck (2). Poromas are distinguished both by the layers of the skin in which they are found and may show either eccrine or apocrine differentiation (1). Compound poromas occupy space in both the epidermis and dermis; hidroaconthomas are epidermal, and dermal duct tumors are confined to the dermis. The predominant type of sweat gland in the external auditory canal is the apocrine gland; however, our patient’s tumor was of eccrine origin. Apocrine poromas can be differentiated from eccrine variants by their greater cytoplasmic eosinophilia. Histologic examination of tumor cells for signs of the mechanism of glandular secretion can also differentiate apocrine from eccrine poromas. The secretions of apocrine glands are encased in vesicles within a membrane ‘‘pinched off’’ from the plasma membrane, and thus, apocrine poromas will show evidence of decapitation-type secretion, with a cleaved appearance of the apical portion of the cells. The final pathology for our patient demonstrated findings consistent with the eccrine poroma (3). Rarely, eccrine poromas transform into malignant tumors. This occurs in 1% of these tumors. The average time to transformation is 8.5 years. There have been several case reports describing metastatic spread of malignant eccrine tumors (4). Therefore, early resection of these tumor types is advisable.
CASE PRESENTATION A 60-year-old man was referred for evaluation of a nontender mass in the left external auditory canal that had been present for 2 years. The patient reported infrequent bleeding from the mass. He denied hearing loss, otalgia, otorrhea, dizziness, vertigo, or tinnitus. He had no history of previous otologic surgery, otitis media, or skin cancer. The mass was an erythematous, papular lesion with a smooth surface and distinct borders, measuring 1.0 cm in diameter (Fig. 1A). Computed tomography of the temporal bones without contrast demonstrated no erosion of the external auditory canal or abnormalities of the mastoid or middle ear (Fig. 1B). His audiogram revealed bilateral mild sensorineural hearing loss. The mass was subject to biopsy in the clinic, with findings consistent with the final pathology. The patient was taken to the operating room for excision of the left external auditory canal mass. Frozen sections showed negative margins. A split thickness skin graft harvested from behind the ear was placed over the defect. Postoperatively, the patient healed well without any sequelae or signs of recurrent lesions 6 months after excision. The final pathology showed a juxtadermal proliferation of uniform basaloid cells with regular nuclei that extended in broad columns from the epidermis. There was no peripheral palisading or clefting. The cells were sharply demarcated from adjacent keratinocytes. These findings were consistent with eccrine poroma (Fig. 2, A and B). DISCUSSION
REFERENCES
Poromas are benign adnexal neoplasms that show differentiation similar to the acrosyringium (the intraepidermal portion of the sweat gland duct). Poromas account
1. Sawaya JL, Khachemoune A. Poroma: a review of eccrine, apocrine, and malignant forms. Int J Dermatol 2014;53:1053Y61. 2. Moore TO, Orman HL, Orman SK, et al. Poromas of the head and neck. J Am Acad Dermatol 2001;44:48Y52. 3. Harada T, Miyamoto T, Takahashi M, et al. Eccrine poroma in the external auditory canal. Otolaryngol Head Neck Surg 2003; 128:439Y40. 4. Robson A, Greene J, Ansari N, et al. Eccrine porocarcinoma (malignant eccrine poroma): a clinicopathologic study of 69 cases. Am J Surg Pathol 2001;25:710Y20.
Address correspondence and reprint requests to Pamela C. Roehm, M.D., Ph.D., Department of OtolaryngologyYHead and Neck Surgery, Temple University School of Medicine, 3509 N. Broad Street, Kresge West, Suite 300, Philadelphia, PA 19140; E-mail: [email protected] The authors disclose no conflicts of interest.
e142
Copyright © 2015 Otology & Neurotology, Inc. Unauthorized reproduction of this article is prohibited.
POROMA OF THE EXTERNAL AUDITORY CANAL
FIG. 1.
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Intraoperative photograph (A) and preoperative temporal bone CT (B) of erythematous mass of the external auditory canal.
FIG. 2. Histologic sections of the mass taken during final excision (hematoxylin and eosin stain). A, Lower power (100) magnification view showing a proliferation of uniform basaloid cells (asterisks) extending from the epidermis in broad columns, which are sharply demarcated from the overlying skin keratinocytes (arrowheads). The nuclei are sharp and regular. The cytoplasm is modest in amount. B, Higher power (200) magnification view of basaloid cells of the tumor, demonstrating cytologically bland nuclear features.
Otology & Neurotology, Vol. 36, No. 8, 2015
Copyright © 2015 Otology & Neurotology, Inc. Unauthorized reproduction of this article is prohibited.
Temporal Bone Histopathology Case of the Month
Eccrine Poroma of the External Auditory Canal *Steven Zuniga, †Jasvir S. Khurana, and *Pamela C. Roehm *Departments of Otolaryngology and ÞPathology, Temple University School of Medicine, Philadelphia, Pennsylvania, U.S.A.
for less than 1% of primary cutaneous lesions (1). Up to 30% of these lesions are found on the head and neck (2). Poromas are distinguished both by the layers of the skin in which they are found and may show either eccrine or apocrine differentiation (1). Compound poromas occupy space in both the epidermis and dermis; hidroaconthomas are epidermal, and dermal duct tumors are confined to the dermis. The predominant type of sweat gland in the external auditory canal is the apocrine gland; however, our patient’s tumor was of eccrine origin. Apocrine poromas can be differentiated from eccrine variants by their greater cytoplasmic eosinophilia. Histologic examination of tumor cells for signs of the mechanism of glandular secretion can also differentiate apocrine from eccrine poromas. The secretions of apocrine glands are encased in vesicles within a membrane ‘‘pinched off’’ from the plasma membrane, and thus, apocrine poromas will show evidence of decapitation-type secretion, with a cleaved appearance of the apical portion of the cells. The final pathology for our patient demonstrated findings consistent with the eccrine poroma (3). Rarely, eccrine poromas transform into malignant tumors. This occurs in 1% of these tumors. The average time to transformation is 8.5 years. There have been several case reports describing metastatic spread of malignant eccrine tumors (4). Therefore, early resection of these tumor types is advisable.
CASE PRESENTATION A 60-year-old man was referred for evaluation of a nontender mass in the left external auditory canal that had been present for 2 years. The patient reported infrequent bleeding from the mass. He denied hearing loss, otalgia, otorrhea, dizziness, vertigo, or tinnitus. He had no history of previous otologic surgery, otitis media, or skin cancer. The mass was an erythematous, papular lesion with a smooth surface and distinct borders, measuring 1.0 cm in diameter (Fig. 1A). Computed tomography of the temporal bones without contrast demonstrated no erosion of the external auditory canal or abnormalities of the mastoid or middle ear (Fig. 1B). His audiogram revealed bilateral mild sensorineural hearing loss. The mass was subject to biopsy in the clinic, with findings consistent with the final pathology. The patient was taken to the operating room for excision of the left external auditory canal mass. Frozen sections showed negative margins. A split thickness skin graft harvested from behind the ear was placed over the defect. Postoperatively, the patient healed well without any sequelae or signs of recurrent lesions 6 months after excision. The final pathology showed a juxtadermal proliferation of uniform basaloid cells with regular nuclei that extended in broad columns from the epidermis. There was no peripheral palisading or clefting. The cells were sharply demarcated from adjacent keratinocytes. These findings were consistent with eccrine poroma (Fig. 2, A and B). DISCUSSION
REFERENCES
Poromas are benign adnexal neoplasms that show differentiation similar to the acrosyringium (the intraepidermal portion of the sweat gland duct). Poromas account
1. Sawaya JL, Khachemoune A. Poroma: a review of eccrine, apocrine, and malignant forms. Int J Dermatol 2014;53:1053Y61. 2. Moore TO, Orman HL, Orman SK, et al. Poromas of the head and neck. J Am Acad Dermatol 2001;44:48Y52. 3. Harada T, Miyamoto T, Takahashi M, et al. Eccrine poroma in the external auditory canal. Otolaryngol Head Neck Surg 2003; 128:439Y40. 4. Robson A, Greene J, Ansari N, et al. Eccrine porocarcinoma (malignant eccrine poroma): a clinicopathologic study of 69 cases. Am J Surg Pathol 2001;25:710Y20.
Address correspondence and reprint requests to Pamela C. Roehm, M.D., Ph.D., Department of OtolaryngologyYHead and Neck Surgery, Temple University School of Medicine, 3509 N. Broad Street, Kresge West, Suite 300, Philadelphia, PA 19140; E-mail: [email protected] The authors disclose no conflicts of interest.
e142
Copyright © 2015 Otology & Neurotology, Inc. Unauthorized reproduction of this article is prohibited.
POROMA OF THE EXTERNAL AUDITORY CANAL
FIG. 1.
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Intraoperative photograph (A) and preoperative temporal bone CT (B) of erythematous mass of the external auditory canal.
FIG. 2. Histologic sections of the mass taken during final excision (hematoxylin and eosin stain). A, Lower power (100) magnification view showing a proliferation of uniform basaloid cells (asterisks) extending from the epidermis in broad columns, which are sharply demarcated from the overlying skin keratinocytes (arrowheads). The nuclei are sharp and regular. The cytoplasm is modest in amount. B, Higher power (200) magnification view of basaloid cells of the tumor, demonstrating cytologically bland nuclear features.
Otology & Neurotology, Vol. 36, No. 8, 2015
Copyright © 2015 Otology & Neurotology, Inc. Unauthorized reproduction of this article is prohibited.
