Final Diagnosis -- Squamoid Cccrine Ductal Carcinoma


DIAGNOSIS

Squamoid eccrine ductal carcinoma

DISCUSSION

Eccrine carcinomas comprise around 0.01% of all tumors and encompasses malignancies which originate from the eccrine glands(1). Squamoid eccrine ductal carcinoma (SEDC) was first described by Wong et al in 1997 for lesions which show eccrine ductal differentiation along with a prominent squamous component (2, 3). It is a rare tumor and with only few cases reported in the English literature. The largest series discussing about the SEDC is from Van der Horst et al (4) in 2016. SEDC has been frequently misdiagnosed as the squamous cell carcinoma (SCC) and other eccrine tumors. We present an interesting case of an elderly man who was simultaneously diagnosed with basal cell carcinoma (BCC) and SEDC.

SEDC are rare tumors and are usually seen in seventh to eighth decade with an age range of 30-91 years. The tumor shows a slight male predominance (3-5) and usually presents as a slow growing nodule or plaque with ulceration or crusting and most frequently involving the head and neck region(3, 5). Few cases have been reported to involve extremities and trunk (4). These tumors have been reported to be present for years sometime up to 10 years before being diagnosed (3, 6). The clinical presentation of these tumors is nonspecific and are clinically thought to be BCC or SCC (4). Our patient also complained of a long-standing, non-healing ulcerated lesion which was clinically thought to be BCC.

Histologically the tumor exhibits a biphasic pattern of growth with the superficial component showing close resemblance to squamous cell carcinoma while the deeper component showing evidence of duct differentiation with features of eccrine ductal carcinoma (3, 4). These tumors shows marked cytologic atypia with desmoplastic stroma and cords of deeply infiltrative tumor cells extending into the dermis and subcutaneous tissue (7). Mitoses can be frequently seen along with perineural invasion. Rarely tumor necrosis and evidence of lymphovascular invasion may be present (8). Our case showed presence of frequent mitosis with few atypical mitosis and foci of tumor necrosis with evidence of perineural invasion.

The differential diagnosis includes squamous cell carcinoma, porocarcinoma with squamous differentiation, microcytic adnexal carcinoma, and also cutaneous metastasis from visceral tumors(1). Adequate sampling and histologic examination are necessary to demonstrate the ductal differentiation in the deeper component to avoid misdiagnosing this tumor as squamous cell carcinoma. Chhibber et al, reported a case of SEDC which was misdiagnosed as SCC multiple times on biopsy sample (1, 5).

Porocarcinoma usually affects the lower extremity while SEDC predominantly involves the head and neck region and shows presence of tumor cells having poroid characteristics, in a background of a pre-existing poroma (8). Microcystic adnexal carcinoma usually show presence of keratinous cystic structures and lacks significant cytologic atypia which are helpful in differentiating it from SEDC (4, 6). Positivity for p63 immunostain favors a primary cutaneous sweat gland carcinoma over a metastatic adenocarcinoma to the skin (9). Our case demonstrated positive staining for p63 along with negative mucicarmine favoring a primary cutaneous malignancy rather than metastatic disease. Luminal differentiation can be demonstrated using epithelial membrane antigen (EMA) and carcinoembryonic antigen (CEA) immunostains. As EMA and CEA are typically seen in glandular tissue positivity for these immunostains is supportive of an adnexal origin and are typically negative in epithelial malignancies such as SCC (10).

SEDC is regarded to have a low-grade malignant potential with few cases showing involvement of regional lymph nodes. However, the risk for local recurrence is high due to underestimation of size on gross examination, deeply infiltrative nature of the tumor and perineural invasion (5). There incidence of local recurrence in this tumor has been reported close to 25% (4). Kim et al has reported local recurrence rate of 10 to 70 percent after conventional excision and 0 to 5 percent after Moh's micrographic surgery (MMS) at an average of 30.9 months follow up (8, 11). There is also significant risk for metastasis to lymph nodes with rates approaching 13% (4). MMS has been suggested as an effective and tissue-sparing surgical modality by few authors (5). The disease-related mortality has not yet been reported in the literature, and the true biologic potential of these tumors is still unknown due to lack of larger studies with long follow-up. We think the tumor needs wide surgical excision with wide negative margins along with close clinical follow-up.

REFERENCES

  1. Chhibber V, Lyle S, Mahalingam M. Ductal eccrine carcinoma with squamous differentiation: apropos a case. J Cutan Pathol. 2007;34(6):503-7.
  2. Wong TY, Suster S, Mihm MC. Squamoid eccrine ductal carcinoma. Histopathology. 1997;30(3):288-93.
  3. Frouin E, Vignon-Pennamen MD, Balme B, Cavelier-Balloy B, Zimmermann U, Ortonne N, et al. Anatomoclinical study of 30 cases of sclerosing sweat duct carcinomas (microcystic adnexal carcinoma, syringomatous carcinoma and squamoid eccrine ductal carcinoma). J Eur Acad Dermatol Venereol. 2015;29(10):1978-94.
  4. van der Horst MP, Garcia-Herrera A, Markiewicz D, Martin B, Calonje E, Brenn T. Squamoid Eccrine Ductal Carcinoma: A Clinicopathologic Study of 30 Cases. Am J Surg Pathol. 2016;40(6):755-60.
  5. Clark S, Young A, Piatigorsky E, Ravitskiy L. Mohs micrographic surgery in the setting of squamoid eccrine ductal carcinoma: addressing a diagnostic and therapeutic challenge. J Clin Aesthet Dermatol. 2013;6(4):33-6.
  6. Chan H, Howard V, Moir D, Dyall-Smith D. Squamoid eccrine ductal carcinoma of the scalp. Australas J Dermatol. 2016;57(3):e117-9.
  7. Herrero J, Monteagudo C, Jorda E, Llombart-Bosch A. Squamoid eccrine ductal carcinoma. Histopathology. 1998;32(5):478-80.
  8. Brenn T. Malignant sweat gland tumors: an update. Adv Anat Pathol. 2015;22(4):242-53.
  9. Qureshi HS, Ormsby AH, Lee MW, Zarbo RJ, Ma CK. The diagnostic utility of p63, CK5/6, CK 7, and CK 20 in distinguishing primary cutaneous adnexal neoplasms from metastatic carcinomas. J Cutan Pathol. 2004;31(2):145-52.
  10. Terushkin E, Leffell DJ, Futoryan T, Cowper S, Lazova R. Squamoid eccrine ductal carcinoma: a case report and review of the literature. Am J Dermatopathol. 2010;32(3):287-92.
  11. Kim YJ, Kim AR, Yu DS. Mohs micrographic surgery for squamoid eccrine ductal carcinoma. Dermatol Surg. 2005;31(11 Pt 1):1462-4.

Contributed by Pooja Srivastava, MD, Katherine Doeden, MD




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