Occult systemic small cell variant ALK-positive anaplastic large cell lymphoma presenting as multiple gastric nodules: A case masquerading as an active inflammatory lesion

초록

We describe a case of small cell variant anaplastic lymphoma kinase (ALK)-positive anaplastic large cell lymphoma (ALCL) that presented as epigastric pain due to gastric mucosal nodules mimicking inflammatory lesions. The patient was a 34-year-old woman presented with epigastric pain and ordynophagia associated with multiple discoid erythematous patches and nodules with surface erosion/ulceration in the stomach, with histologic features raising concerns for infectious gastritis such syphilis or virus. However, the tests for syphilis and virus were negative. The lymptom was intractable to symptomatic treatment and she developed a pathologic compression fracture in thoracic spine. Further imaging studies revealed abdominopelvic lymphadenopathy and several metastatic foci in in the cervical and thoracic vertebral bodies. The biopsies from a pelvic lymph node and the T3 vertebral body showed histologic characteristics of ALK-positive ALCL of small cell variant. Retrospectively, we reviewed the endoscopic gastric biopsies of the patient. With the aid of immunohistochemistry, we were able to recognize the neoplastic infiltrate in the gastric lesions in which the tumor cells appeared as plasmacytoid cells and nondescript small to medium-sized tumor cells with conspicuous mitotic activity and diffuse strong expression of CD30 and ALK. This case illustrates a potential diagnostic pitfall in the differential diagnosis of ALCL of small cell variant to which a pathologist can be unavoidably and unintentionally blind.