
Signet Rings Beyond the Norm: A Report of Two Rare Cases
ED06-ED10
Correspondence
Dr. Gramani Arumugam Vasugi,
Associate Professor, Department of Pathology, Sri Ramachandra Medical College and Research Institute, SRIHER, Chennai-600116, Tamil Nadu, India.
E-mail: gvasugi@sriramachandra.edu.in
Pulmonary adenocarcinoma with Signet Ring Cell (SRC) morphology is a very rare and distinct subtype initially classified as signet ring adenocarcinoma in the 2004 World Health Organisation (WHO) classification of lung tumours. In the 2015 classification, however, it was removed as a distinct variant. SRC morphology is characterised by abundant intracellular mucin and a crescentic nucleus and is now considered a cytologic change that may occur in various histological patterns. Here, we present two cases reported over one month. The first case is of a 61-year-old female who presented with shortness of breath, loss of weight and loss of appetite for two months. Positron Emission Tomography-Computerised Tomography (PET/CT) scan showed a well-defined malignant-looking lesion in the right middle lobe with metastasis to the right pleura, lymph nodes, liver and adrenal gland. The core biopsy revealed the diagnosis of lung adenocarcinoma with SRC morphology, which was confirmed by Immunohistochemistry (IHC) which also demonstrated positivity for Anaplastic large cell Lymphoma Kinase (ALK) gene rearrangement. The second case was of a 62-year-old female who presented with breathlessness, cough with expectoration and loss of weight for the past six months. PET/CT done outside showed a Fluorodeoxyglucose (FDG) avid lesion measuring 2.3×1.6×1.0 cm, involving the left lower lobe, favouring lung carcinoma, with multiple enlarged lymph nodes. Core biopsy of the lesion revealed the diagnosis of lung adenocarcinoma with SRC morphology. Further, IHC work-up confirmed the diagnosis. Metastasis from other primary sites should be considered first since SRC carcinoma can commonly appear in various organs, including the stomach, colon, urinary bladder, prostate and breast. The presence of Thyroid Transcription Factor-1 (TTF-1) and Cytokeratin 7 (CK7) positivity supports a primary lung adenocarcinoma diagnosis. This variant is found alongside classic adenocarcinoma and frequently metastasises to lymph nodes harbouring ALK gene rearrangements. This case highlights the importance of recognising this distinct clinical entity within pulmonary adenocarcinoma due to its aggressive behaviour and the necessity for timely and accurate diagnosis for targeted treatment.