# Anaplastic Lymphoma Kinase (ALK)-Negative Anaplastic Large Cell Non-Hodgkin Lymphoma as a Rare Differential Diagnosis of Lung Cancer: A Case Report

## TL;DR

This case report describes a rare diagnosis of ALK-negative anaplastic large cell lymphoma mistaken for lung cancer in a 72-year-old man.

## Contribution

The paper highlights the diagnostic challenge of ALK-negative ALCL as a rare differential diagnosis of lung cancer.

## Key findings

- The patient's symptoms and initial biopsy suggested metastatic adenocarcinoma.
- Immunohistochemistry confirmed ALK-negative anaplastic large cell non-Hodgkin lymphoma.
- The case underscores the need for accurate diagnosis due to the disease's poor prognosis.

## Abstract

Anaplastic large cell lymphomas (ALCL) are a group of sporadic malignancies that generally have an aggressive clinical course, especially the subtype of anaplastic lymphoma kinase (ALK)-negative ALCL. The appropriate diagnostic study modalities must be chosen to make an accurate diagnosis and promptly initiate specific treatment. We present the clinical case of a 72-year-old male patient with dyspnea on small efforts accompanied by diaphoresis and a weight loss of 10 kg in two months. Physical examination revealed adenopathy in the cervical region and bilateral pleural effusion. The pleural and lung biopsies revealed poorly differentiated metastatic adenocarcinomas. A multidisciplinary analysis was carried out; the typical clinical-radiographic presentation of adenocarcinoma was ruled out with immunohistochemistry, thus determining a diagnosis of ALK-negative anaplastic large cell non-Hodgkin's lymphoma. This case represented a diagnostic and therapeutic challenge since it is a rare entity with a poor prognosis, and there are only a few studies about the choice of appropriate chemotherapy in these patients.