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Year : 2021  |  Volume : 64  |  Issue : 1  |  Page : 186-188
A case of eccrine porocarcinoma: A treacherous mimic and diagnostic challenge

1 Department of Pathology, Calcutta National Medical College, Siliguri, West Bengal, India
2 Department of Pathology, Institute of Post Graduate Medical Education and Research, Siliguri, West Bengal, India
3 Dermatology, Calcutta National Medical College, Siliguri, West Bengal, India

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Date of Submission30-May-2019
Date of Decision09-Dec-2019
Date of Acceptance16-Dec-2019
Date of Web Publication8-Jan-2021


Eccrine porocarcinoma is a rare malignant dermal appendageal tumor notorious for its varied morphology, both clinically and histologically; and it can pose a considerable diagnostic dilemma to both the dermatologist and the pathologist. Herein, we present a case of a 74-year-old woman with slow-growing nodular masses on both buttocks, reaching a fairly large size over a course of 3 years. Although atypical morphologic features posed significant diagnostic difficulty to both the surgeon and the pathologists, it was eventually diagnosed as eccrine porocarcinoma with focal squamoid features, using immunostains. To our knowledge, this is the second reported case of bilateral eccrine porocarcinoma which highlights the need for awareness of the morphological variations that this entity is capable of producing.

Keywords: Adnexal carcinoma, porocarcinoma, porocarcinoma mimics

How to cite this article:
Das D, Datta C, Chatterjee U, De A. A case of eccrine porocarcinoma: A treacherous mimic and diagnostic challenge. Indian J Pathol Microbiol 2021;64:186-8

How to cite this URL:
Das D, Datta C, Chatterjee U, De A. A case of eccrine porocarcinoma: A treacherous mimic and diagnostic challenge. Indian J Pathol Microbiol [serial online] 2021 [cited 2021 May 10];64:186-8. Available from: https://www.ijpmonline.org/text.asp?2021/64/1/186/306517

   Introduction Top

Eccrine porocarcinoma is a rare malignant tumor of the sweat gland, originating from the intraepidermal and dermal eccrine ducts. The entity was first described by Pinkus and Mehregan in 1963.[1] It can pose significant diagnostic difficulty to both the dermatologist and the pathologist, owing to its staggering clinical and histological variations. Herein, we report the case of a patient with tumors arising on both buttocks, initially reported on FNAC and incisional biopsy as malignant melanoma, and later confirmed to be a case of eccrine porocarcinoma. This case, to our knowledge, is the second reported case of bilateral porocarcinoma.[2]

   Case Report Top

A 74-year-old lady presented with nonpruritic nodular lesions on both buttocks, measuring 14 cm × 7 cm and 10 cm × 10 cm, respectively, slowly growing to its present size over a course of 3 years [Figure 1]. On examination, no palpable lymph nodes were found in the inguinal or other regions in the body. Except for mild pallor, general examination revealed no abnormalities or systemic diseases. The patient had no history of significant exposure to the sun, industrial chemicals, immunosuppressants, or irradiation.
Figure 1: Preoperative picture showing a large lesion spread over both buttocks, having become confluent in the middle. The peripheral area has a thick plaque-like appearance and the central area is nodular, with ulceration at places

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She was presented to the dermatologists with an FNAC report of “malignant lesion: possibly malignant melanoma”, and an incisional biopsy report of “malignant melanoma”, both done approximately 2 months previously. These tests were done from other institutes and were reported on the basis of morphology alone, without any immunohistochemical aids. The slides were not available for review. Dermatologic and surgical consultants performed a wide excision and the entire specimen was sent to us for histopathological examination.

Multiple sections from both the resected masses revealed similar histologic features of a tumor predominantly composed of large round-to-oval cells with eosinophilic-to-clear cytoplasm, sharp cytoplasmic borders, and a large nucleus with vesicular chromatin, prominent nucleolus, and frequent mitotic figures. The cells were mostly arranged in cords, anastomosing trabeculae, and solid sheets with clear infiltrative pattern [Figure 2]a. Widespread ductal differentiation and focal squamoid differentiation with pearl formation were also noted [Figure 2]c and [Figure 2]d. Prominent Paget phenomenon was present throughout the lesion [Figure 2]a and [Figure 2]b, which possibly led to the previous diagnosis of malignant melanoma in the small incisional biopsy. Lymphovascular invasion was present and resection margins were involved on both sides.
Figure 2: Eccrine porocarcinoma. [a] Anastomosing cords of neoplastic cells showing dermal infiltration. H and E, ×100. [b] Higher magnification showing cellular atypia and prominent Paget phenomenon. H and E, ×100. [c] Focal squamoid differentiation with pearl formation. H and E, x400. [d] Ductal differentiation of the malignant cells. H and E, ×100

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The differential diagnoses of porocarcinoma, malignant melanoma, and acantholytic squamous cell carcinoma were considered.

The tumor cells were positive for Periodic-Acid-Schiff (PAS) reaction with diastase digestion. HMB45 and Melan-A were negative, while only very few scattered S100 positive cells were found in the lesion. Epithelial membrane antigen (EMA) was strongly and diffusely positive in the malignant cells. The tumor cells were also diffusely positive for pancytokeratin and CK7 [Figure 3].
Figure 3: Immunohistochemistry panel. [a] CK7: Strongly positive in neoplastic cells as compared to the overlying epithelium, ×100. [b] EMA: Strongly positive in the tumor cells, ×100. [c] EMA: Higher magnification showing cytoplasmic and membrane positivity of EMA, ×400. [d] S100: Tumor cells are negative for S100 staining, ×400

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Based on the histology, immunohistochemical staining patterns, and clinical features, a diagnosis of bilateral eccrine porocarcinoma was made. A re-excision for positive margin status was done, followed by skin grafting. Her wounds healed within a few months. PET-CT scan done at 9 months revealed no recurrence or metastasis.

   Discussion Top

Eccrine porocarcinomas are usually presented as slow-growing lesions, appearing as verrucous plaques or ulcerated nodules, commonly on the lower limbs, trunk, head and neck, or other areas including the genitalia.[3] Lymph nodal metastasis can be found in up to 20% cases, whereas distant metastasis has been recorded in up to 10% patients. The tumors often show a prolonged clinical course, reaching up to 50 years, presumably because they can develop in a preexisting benign adnexal tumor-like poroma.[4] Usually presenting in the 6th to 8th decade of life, this tumor has a broad reported age range, starting from 8 years, and extending up to 90 years.[5] The only other bilateral eccrine porocarcinoma reported in literature occurred as multiple lesions on the dorsa of both feet of an 82-year-old lady.[2]

For this type of tumor, the initial findings can be misleading, owing to its diagnostic challenge to the morphologic variety, indolent behavior, and its rarity. Indeed, eccrine porocarcinoma can show basal or squamoid or even spindle cell differentiation, presence of clear cells, mucous cell metaplasia, melanocytic colonization, and Paget phenomenon, rendering a variety of histological differential diagnoses such as other cutaneous adnexal neoplasms, basal cell carcinoma, squamous cell carcinoma, malignant melanoma, cutaneous sarcomas, and metastatic adenocarcinomas.[4],[6] To complicate matters, recurrent or metastatic lesions may show dedifferentiation and a lack of its hallmark ductal differentiation.[7]

The malignant cells of eccrine porocarcinoma are usually diffusely positive for pancytokeratin (AE1/AE3), with positivity of EMA and CEA in the luminal rims of the ductal structures. Scattered dendritic melanocytes may be positive for S100 and HMB45, which help to differentiate it from malignant melanoma and also from myoepithelial lineage tumors (e.g., eccrine acrospiroma, eccrine spiradenoma, and dermal mixed tumor), in which it is the neoplastic cells that are S100 positive.[7]

Tumor depth more than 7 mm, lymphovascular invasion, and high mitotic count (>14 mitotic figures/high power field) are some of the documented adverse prognostic factors that may guide management options.[4]

Proper treatment guidelines regarding mode of surgery and use of adjuvant therapy are still lacking as available database remains small.[5] However, newer molecular techniques are bringing up potential targeted therapies, as more tumors are undergoing molecular profiling everyday. TP53 alterations, p16INK4 expression abnormalities, PTEN copy loss, EGFR overexpression, and RAS pathway overactivation are a few findings that may have potential bearing on the adoption of future prognostic and predictive markers for this tumor.[8]

Eccrine porocarcinoma remains an entity rarely encountered in regular dermatology as well as surgical pathology practices, and bears a risk of misdiagnosis from both sides. This case highlights unusual morphologic features such as prominent Paget phenomenon, squamous metaplasia, and subtle duct formation, all of which can pose a significant diagnostic dilemma to the pathologist.

   Conclusion Top

Dermatologists, oncologists, and especially the pathologists need to be aware of eccrine porocarcinoma, and perform basic immunohistochemical workup in small biopsies with atypical features to rule out the possibility of missing such a lesion.

In the future, IHC studies and molecular profiling of each tumor may help in personalizing therapeutic options for patients and further studies for identifying such predictive markers on a large scale are the need of the hour.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

Financial support and sponsorship


Conflicts of interest

There are no conflicts of interest.

   References Top

Pinkus H, Mehregan AH. Epidermotropic eccrine carcinoma. Arch Dermatol 1963;88:597-606.  Back to cited text no. 1
Kutty A, Harper F, Akhras V. Treatment of multiple bilateral primary eccrine porocarcinoma with topical diphencyprone: A case report. Br J Dermatol 2013;169:1159-61.  Back to cited text no. 2
Riera Leal L, Guevara-Gutiérrez E, Barrientos-García JG, Madrigal-Kasem R, Briseño-Rodríguez G, Tlacuilo-Parra A. Eccrine porocarcinoma: Epidemiologic and histopathologic characteristics. Int J Dermatol 2015;54:580-6.  Back to cited text no. 3
Robson A, Greene J, Ansari N, Kim B, Seed PT, McKee PH, et al. Eccrine porocarcinoma (malignant eccrine poroma): A clinicopathologic study of 69 cases. Am J Surg Pathol 2001;25:710-20.  Back to cited text no. 4
Parmar N, Mohamed M, Elmoghrabi A, McCann M. Eccrine Porocarcinoma presenting as an abdominal wall mass in a patient with ulcerative colitis—A rare case report. Int J Surg Case Rep 2016;23:40-3.  Back to cited text no. 5
De Almeida Luz M, Ogata DC, Montenegro MF, Biasi LJ, Ribeiro LC. Eccrine porocarcinoma (malignant eccrine poroma): A series of eight challenging cases. Clinics 2010;65:739-42.  Back to cited text no. 6
Kurisu Y, Tsuji M, Yasuda E, Shibayama Y. A case of eccrine porocarcinoma: Usefulness of immunostain for S-100 protein in the diagnoses of recurrent and metastatic dedifferentiated lesions. Ann Dermatol 2013;25:348-51.  Back to cited text no. 7
Thibodeau ML, Bonakdar M, Zhao E, Mungall KL, Reisle C, Zhang W, et al. Whole genome and whole transcriptome genomic profiling of a metastatic eccrine porocarcinoma. NPJ Precis Oncol 2018;2:8.  Back to cited text no. 8

Correspondence Address:
Diya Das
Department of Pathology, Calcutta National Medical College, Kolkata, West Bengal
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/IJPM.IJPM_427_19

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