HN Sweat Gland Adenocarcinoma Rare, But Locally Aggressive

by Samara E. Kuehne •

What are the demographics and clinicopathologic traits of head and neck sweat gland adenocarcinoma (HNSGA), and what are the poor prognostic indicators?

Bottom line
HNSGA are locally aggressive tumors that most commonly occur on the face. Although regional and distant disease are rare on presentation, their presence predicts poorer outcomes. Other negative prognostic factors include older age, scalp and neck location, and histologically high-grade tumors.

Background: The literature on HNSGA is limited. Sweat gland adenocarcinoma (SGA) is a rare adnexal tumor that most commonly arises in the palms and soles, and historically has been difficult to study due to the limited cases available in the literature, as well as the challenge in classifying this heterogeneous group of tumors. SGA usually begins as a painless red or violet papule that gradually progresses to a solid infiltrating nodule. SGA can spread via the lymphatics; common sites of distant metastases include liver, lung, and bone. The treatment of choice is wide surgical excision, with regional lymph node dissection when there is nodal metastasis. The efficacy of adjuvant chemotherapy and radiotherapy is controversial.

Study design: Retrospective population-based analysis.

Synopsis: Using the Surveillance, Epidemiology, and End Results registry from 2000 to 2013, the authors identified 627 cases of HNSGA. Data were analyzed for incidence trends, demographic and clinicopathologic traits, and predictors of disease-specific survival (DSS). The majority of HNSGA cases were white, male, and 60 to 79 years old. The incidence was 0.036 per 100,000 people. Tumors most often presented as localized disease and histological grade II/III. The skin of the face was the most common primary site (43.4%), followed by the scalp and neck (31.6%). Overall 5-, 10-, and 20-year DSS were 94.6%, 89.6%, and 79.8%, respectively. Ethnicity did not affect survival, whereas a younger age at diagnosis and female sex conferred an advantage at 10 years and five years, respectively. The origin of the HNSGA (apocrine vs. eccrine) did not affect outcomes. Regional and distant disease predicted worse DSS at five, 10, and 20 years. Compared with grade I/II disease, grade III/IV dramatically worsened five-, 10-, and 20-year DSS. Scalp and neck HNSGA exhibited the poorest 20-year DSS compared with other primary sites.

This analysis suggests that HNSGA typically is identified early in its progression and mostly appears to be locally aggressive in behavior. Although there is no established algorithm for the treatment of SGA, there is general consensus in the literature that primary surgical excision with wide margins (1 cm–2 cm) and therapeutic neck dissection in the presence of clinically positive nodes is the recommended treatment.