Central Nervous System -Invading Eccrine Gland Carcinoma: A Clinicopathologic Case Series and Literature Review

Background Eccrine carcinoma involvement of the central nervous system (CNS) is exceedingly rare. The prognosis and response to treatment of this pathology remain poorly characterized. Methods A retrospective case series and literature review were conducted. Results CNS-invading eccrine carcinoma was diagnosed in 3 patients (2 male and 1 female; age range, 60–79 years), including 2 cases of brain metastases and 1 case of brain-invading skull metastasis with subsequent spinal metastasis. The interval from primary tumor to CNS invasion was 18–51 months. All patients received multimodal therapy following diagnosis of CNS involvement. One patient who harbored a NOTCH1 mutation demonstrated a durable oncologic response after treatment with the immune checkpoint inhibitor pembrolizumab and lived 39 months after CNS invasion. The other 2 patients were discharged to hospice care within 1 month after the diagnosis of eccrine carcinoma brain metastasis. Including this case series, 23 cases of eccrine carcinoma invasion or metastasis to the CNS have been reported, with survival after diagnosis of CNS involvement ranging from a few weeks to 4 years. Conclusions We present 3 cases of eccrine carcinoma metastatic to the CNS, including the first reported case to our knowledge of eccrine carcinoma treated with immunotherapy. This case, harboring a NOTCH1 mutation, demonstrated the longest durable oncologic response reported in this rare disease. Genomic and molecular testing may play increasingly important roles in the evaluation of these metastases.