Eccrine Porocarcinoma, A Rare Aggressive Malignant Adnexal Tumor of the Skin: A Case Report

We present a case of 71-year-old male who presented with a painless nodular growth on the lateral aspect of left thigh. MRI was suggestive of irregular exophytic lesion in the left gluteal region with enlarged left inguinal nodes. Biopsy suggested malignant adnexal tumor- porocarcinoma. Patient underwent wide local excision followed by adjuvant chemotherapy and radiation. In spite of the aggressive management, patient had a local disease recurrence within 3 months.


Introduction
Eccrine porocarcinoma (EPC) is a rare tumor which was initially described by Pinkus and Mehregan as epidermotropic eccrine carcinoma [1,2]. It develops from the intraepidermal ductal portion of the eccrine sweat gland [3]. 20% of these tumors are considered to be aggressive and Metastasis occurred less frequently. Literature regarding the appropriate management of this tumor is lacking due to the rarity of the disease. We report a case of Porocarcinoma of Left thigh which recurred in 3months despite aggressive management with combined modality.

Case Report
A 71-year-old male patient presented with a 3cm nodular painless growth on the lateral aspect of left thigh. Patient apparently noticed this painless swelling 2 years ago which gradually increased in size, without any associated symptoms. Patient noticed bleeding from the growth which was managed conservatively. Subsequently the patient underwent MRI which showed an irregular exophytic cutaneous altered signal intensity lesion in the left gluteal region laterally with mild adjacent subcutaneous edema with enlarged left inguinal nodes. Biopsy was performed which was suggestive of Malignant epithelial neoplasm, morphology suggestive of malignant adnexal tumorporocarcinoma. Staging workup was done with PET CT scan which showed 48X25X50mm metabolically active heterogeneously enhancing exophytic cutaneous lesion in the lateral aspect of the left gluteal region with mildly avid enlarged left inguinal nodes. After discussing in the multidisciplinary tumor board, Patient was started on adjuvant chemotherapy with Mitomycin-C and 5FU for 6 cycles with EBRT of 60Gy in 30 fractions to the surgical bed. Patient tolerated treatment well with very little treatment related toxicity. PET-CT scan was performed 3 months after completion of the treatment and it was negative for active disease. Subsequent scan at 6 months showed a left inguinal nodal recurrence and patient was given radiation to the diseased node.

Cancer Therapy & Oncology International Journal Discussion
Primary adenocarcinoma arising from the eccrine sweat glands is very rare, representing approximately 0.005 % of epithelial cutaneous neoplasms [1]. It occurs in the elderly, usually after 60 years [4]. The predilection site is the lower extremities (55%), followed by the head and scalp (20%), upper limbs (12%), and trunk and abdomen (10%) [5]. The differential diagnosis with other malignant tumors of the skin is very complex, especially with seborrheic keratosis, Bowen tumor, multifocal basal cell carcinoma, lymphoma, achromic melanoma, pyogenic granuloma, wart, and nevus [6]. Metastasis occurs in about 20% of cases with a very poor outlook and high mortality. Most common site was lymph nodes, lung, retroperitoneum, and liver [7].
The main treatment for localized form is surgical excision with histologically clear margins [8]. Role of adjuvant chemotherapy and radiotherapy is not clearly defined for locally advanced porocarcinoma. Various chemotherapeutic agents like Docetaxel, 5FU, Mitomycin-c, Doxorubicin, Vincristine, cyclophosphamide is known to be effective but sufficient data is not available to standardize the treatment. Effectiveness of radiotherapy is unknown and the available data is controversial regarding its role in the management of porocarcinoma. Our patient underwent wide local excision with ilioinguinal dissection and in view of positive nodes, adjuvant chemotherapy and radiotherapy were administered following which patient showed complete response but subsequently the patient had regional nodal recurrence for which he was irradiated.

Conclusion
Eccrine porocarcinoma is a rare malignant adnexal tumor of skin which is diagnosed based on the morphological characteristics. Management is primarily surgical excision and if clinically nodes are detected, lymphadenectomy should be considered. Although data regarding adjuvant treatment is unknown, our patient was managed aggressively with adjuvant chemotherapy and radiotherapy as he was deemed as high risk for recurrence. In spite of this aggressive management, patients developed nodal recurrence within 6 months which suggests the aggressive nature of the disease.