Differentiating Hodgkin Lymphoma and Sarcoid Reaction in Subsequent FDG-PET/CT: A Case Report and Literature Review

Sarcoidosis is frequently associated with various hematological and solid tumors; it can be discovered by chance during tumor evaluations. Sarcoidosis can occur before some cancers, coexist with others, or be diagnosed 1 to 2 years later. Sarcoid reaction affecting hilar and mediastinal lymph nodes can pose a diagnostic challenge in patients with histopathological confirmation of Hodgkin lymphoma who are being evaluated using fluorodeoxyglucose-positron emission tomography computed tomography (FDG-PET/CT) scan because it cannot be easily distinguished from lymphoma infiltration. The presence of an increase or persistence of a prominent activity on a follow-up FDG-PET/CT scan after chemotherapy treatment for lymphoma that is associated with a complete metabolic response in the site of the primarily diagnosed lymphomatous disease is highly suggestive of concurrent sarcoidosis and necessitates careful assessment to avoid unnecessary therapy.

Sarcoidosis and sarcoidal foreign body reaction after permanent eye makeup application: Analysis by immunohistochemistry with commercially available antibodies specific to Cutibacterium acnes and Mycobacteria

We report two cases of eyebrow granulomas in patients who underwent a permanent eye makeup procedure. A rash was observed 16 months after the procedure in case 1 and 10 years after the procedure in case 2. Histopathologically, both patients exhibited non-caseating epithelioid cell granulomas. In case 1, most of the black-brown granules of the permanent makeup were not present in the granulomas but were localized in the upper dermis. In contrast, in case 2, some of the black-brown granules were phagocytized in the granulomas, preferentially within the giant cells. Based on systemic examinations, the patients from cases 1 and 2 were diagnosed with sarcoidosis and sarcoidal foreign body reaction, respectively. To clarify the pathogenesis of our cases, we performed immunohistochemistry using commercially available monoclonal antibodies specific to Cutibacterium acnes, previously Propionibacterium acnes (PAB), and Mycobacteria (LAM antibody). PAB antibody results were positive in granulomas only in case 1, and the LAM antibody results were negative in both cases. Immunohistochemical detection of C. acnes in granulomas could provide useful information for differentiating between cutaneous sarcoidosis and sarcoidal foreign body reactions.

Gastric Cancer with Multiple Lymph Node Enlargement at the Time of the Sarcoidosis Diagnosis

An 80-year-old woman was found to have a 40-mm depressed-type gastric cancer. Computed tomography showed multiple lymph node enlargement, including paraaortic lymph nodes. The extent of lymph node enlargement was significant compared with the depth of the primary lesion. We conducted distal gastrectomy, D2 lymph node dissection, and a paraaortic lymph node biopsy. Microscopically, the tumor was diagnosed as mucosal cancer. In the dissected lymph nodes, noncaseating granuloma was found without metastasis of adenocarcinoma. Immunohistochemical staining using Propionibacterium acnes-specific antibodies showed a large number of P. acnes-positive cells in the granulomas. Finally, the tumor was diagnosed as early-stage gastric cancer and sarcoidosis.

Sarcoid-like reaction of the extrathoracic lymph node in a patient with lung adenocarcinoma treated with pembrolizumab

Immune checkpoint inhibitors (ICIs) have become the standard of care for the treatment of non‐small cell lung cancer (NSCLC). With the increasing use of ICIs, clinicians should be familiar with their immune‐related adverse events, including sarcoid‐like reactions, which have been associated with the use of ICIs in patients with cancer. Sarcoid‐like reactions are caused by uncontrolled T helper 1‐mediated immune responses resulting from ICIs, but their pathophysiology is not fully understood. Sarcoid‐like reactions are often clinically important because they mimic metastases from treated cancer. According to previous reports, sarcoid‐like reactions are typically observed in intrathoracic locations (lung and/or mediastinal lymph nodes) and the skin. In this study, we report an extremely rare case of extrathoracic sarcoid‐like reaction in the right external iliac lymph node following two cycles of pembrolizumab therapy in a patient with lung adenocarcinoma. The laboratory data and computed tomography images suggested that infectious and autoimmune diseases were not considered to be the causative agents. Residual bone metastasis might have caused T helper 1‐mediated immune responses by pembrolizumab, and contributed to sarcoid‐like reactions in the right external iliac lymph node. Sarcoid‐like reactions should be considered in the differential diagnosis of patients with lung cancer treated with ICIs who exhibit worsening extrathoracic lymph node swelling. Clinicians should be cautious not to mistake extrathoracic sarcoid‐like reactions of the lymph nodes for progression of the treated disease.