Neoplastic mast cells expressing CD25 and CD2 can be detected in ascites in patients with advanced systemic mastocytosis and ascites, according to a new study published in The Journal of Allergy and Clinical Immunology: In Practice. These cells could, therefore, be potential biomarkers for diagnosis and response to treatment in these patients.

This finding is based on 2 patients with advanced systemic mastocytosis and ascites. 

The first patient was a 72-year-old man who presented with fatigue, weight loss, hepatosplenomegaly, and ascites. The ascites had no metastatic cells but contained CD117-positive mast cells expressing CD25 and CD2. Some of the mast cells were spindle shaped.

The patient was treated with cladribine and palliative radiation for rectal adenocarcinoma. This improved his fatigue, weight loss, and bleeding events and decreased the number of neoplastic mast cells in ascites. However, he relapsed and died 14 months later.  

Read more about the diagnosis of systemic mastocytosis

The second patient was a 62-year-old man who presented with weight loss, recurrent nose bleeds, diarrhea, hepatosplenomegaly, and ascites. The ascites contained CD117-positive mast cells expressing CD25 and CD2 as well as monocytosis and spindle-shaped mast cells. He was treated with allogeneic stem cell transplantation.

However, systemic mastocytosis with an associated hematological neoplasm persisted and progressed. Treatment with midostaurin had no effect on disease progression and caused adverse side effects. Cutaneous graft-versus-host reaction developed and was treated with tacrolimus and prednisone. “The patient is currently in evaluation for a second [allogeneic] transplantation,” the authors reported.

“These observations suggest that ascites [mast cells] . . . might serve as additional diagnostic and treatment response markers in patients with [advanced systemic mastocytosis],” the researchers concluded. Future work could focus on the potential of mast cells isolated from ascites as individual diagnostic and therapeutic response markers in advanced systemic mastocytosis, according to the authors.

Reference

Kirsch M, Stehle GT, Konantz M, et al. Presence of neoplastic mast cells in ascites in advanced systemic mastocytosis. J Allergy Clin Immunol Pract. Published online July 22, 2022. doi:10.1016/j.jaip.2022.07.014