Case Reports

Squamoid Eccrine Ductal Carcinoma

Author and Disclosure Information

Squamoid eccrine ductal carcinoma (SEDC) is an extremely rare cutaneous tumor of unknown etiology. We report the case of a 77-year-old man with a history of treated chronic lymphocytic leukemia along with numerous basal cell and squamous cell carcinomas who presented for evaluation of a 5-cm, stellate, sclerotic plaque on the left chest of approximately 2 years’ duration and a suspicious 3-mm pink papule on the right nasal sidewall of 2 months’ duration. Initial histology of both lesions revealed carcinoma with squamous and ductal differentiation that extended from the undersurface of the epidermis, favoring a diagnosis of SEDC. It was later determined that the patient had distant metastasis of SEDC. This report of an immunocompromised patient with SEDC is a rare case of distant metastasis of SEDC. A review of the literature on the diagnosis, treatment, and surveillance of SEDC also is provided.

Practice Points

  • Squamoid eccrine ductal carcinoma (SEDC) is an extremely rare cutaneous tumor of unknown etiology.
  • A high index of suspicion with SEDC in the differential diagnosis should be maintained in elderly men with slow-growing, solitary, nodular lesions of the scalp, nose, arms, legs, or trunk.
  • Development of a second or even a third primary malignancy in patients with SEDC is increasingly being reported in CLL patients.


 

References

Eccrine carcinomas are uncommon cutaneous neoplasms demonstrating nonuniform histologic features, behavior, and nomenclature. Given the rarity of these tumors, no known criteria by which to diagnose the tumor or guidelines for treatment have been proposed. We report a rare case of an immunocompromised patient with a primary squamoid eccrine ductal carcinoma (SEDC) who was subsequently treated with radical resection and axillary dissection. It was later determined that the patient had distant metastasis of SEDC. A review of the literature on the diagnosis, treatment, and surveillance of SEDC also is provided.

Case Report

A 77-year-old man whose medical history was remarkable for chronic lymphocytic leukemia (CLL) and numerous previous basal cell carcinomas and squamous cell carcinomas (SCCs) presented with a 5-cm, stellate, sclerotic plaque on the left chest of approximately 2 years’ duration (Figure 1) and a 3-mm pink papule on the right nasal sidewall of 2 months’ duration. Initial histology of both lesions revealed carcinoma with squamous and ductal differentiation extending from the undersurface of the epidermis, favoring a diagnosis of SEDC (Figure 2). At the time of initial presentation, the patient also had a 6-mm pink papule on the right chest of several months duration that was consistent with a well-differentiated sebaceous carcinoma on histology.

Figure 1. Squamoid eccrine ductal carcinoma presenting as a 5-cm, stellate, sclerotic plaque on the left chest.
Figure 2. Squamoid eccrine ductal carcinoma. Histology revealed infiltrative nests and cords of squamoid cells with epidermal involvement and some ductal formation within the dermis and subcutis, extending to fat lobules (A and B)(H&E, original magnification ×40 and ×100, respectively). Tumor nests extended to fibrous septae in adipose tissue (C)(H&E stain, original magnification ×100), and subtle tumor nests within a fibromyxoid background in the superficial dermis were noted (D)(H&E, original magnification ×100).

Further analysis of the lesion on the left chest revealed positive staining for cytokeratin (CK) 5/14 and p63, suggestive of a cutaneous malignancy. Staining for S100 protein highlighted rare cells in the basal layer of tumor aggregates. The immunohistochemical profile showed negative staining for CK7, CK5D3, epithelial membrane antigen (EMA), estrogen receptor, progesterone receptor, and human epidermal growth factor 2.

Diagnosis of SEDC of the chest and nasal lesions was based on the morphologic architecture, which included ductal formation noted within the tumor. The chest lesion also had prominent squamoid differentiation. Another histologic feature consistent with SEDC was poorly demarcated, infiltrative neoplastic cells extending into the dermis and subcutis. Although there was some positive focal staining for carcinoembryonic antigen (CEA), variegation within the tumor and the prominent squamoid component might have contributed to this unexpected staining pattern.

The patient was admitted to the hospital for excision of the lesion on the chest wall. Initial workup revealed macrocytic anemia, which required transfusion, and an incidental finding of non–small-cell lung cancer. The chest lesion was unrelated to the non–small-cell lung cancer based on the staining profile. Material from the lung stained positive for thyroid transcription factor 1 (TTF-1) and exhibited rare staining for p63; however, the chest lesion did not stain positive for TTF-1 and had strong staining affinity for p63, indicative of a cutaneous malignancy.

The lesion on the chest wall was definitively excised. Pathologic analysis revealed a dermal-based infiltrative tumor of irregular nests and cords of squamoid cells with focal ductal formation in a fibromyxoid background stroma, suggestive of an adnexal carcinoma with a considerable degree of squamous differentiation and favoring a diagnosis of SEDC. Focal perineural invasion was noted, but no lymphovascular spread was identified; however, metastasis was identified in 1 of 26 axillary lymph nodes. The patient underwent 9 sessions of radiation therapy for the lung cancer and also was given cetuximab.

Three months later, the nasal tumor was subsequently excised in an outpatient procedure, and the final biopsy report indicated a diagnosis of basal cell carcinoma. One-and-a-half years later, in follow-up with surgery after removal of the chest lesion, a 2×3-cm mass was excised from the left neck that demonstrated lymph nodes consistent with metastatic SEDC. Careful evaluation of this patient, including family history and genetic screening, was considered. Our patient continues to follow-up with the dermatology department every 3 months. He has been doing well and has had multiple additional primary SCCs in the subsequent 5 years of follow-up.

Next Article: