Primary Linitis Plastica of the Rectum: Focus on Magnetic Resonance Imaging Patterns and Treatment Options.

BACKGROUND: Rectal linitis plastica (RLP) is a rare disease with poor outcome. It is often accompanied by a delayed histopathological diagnosis, primarily due to submucosal disease. A concentric ring pattern or "target sign" on T2-weighted magnetic resonance imaging (MRI) has been proposed as being characteristic for early suspicion. Even though RLP is more aggressive and has poorer survival than other rectal adenocarcinomas, no specific treatment is recommended. In this case report of 3 patients, we challenge the sensitivity of the characteristic radiological pattern, and we review the existing data for a treatment strategy.

CASE REPORT: One patient presented classic clinical characteristics of RLP with young age and advanced stage at diagnosis, with chemo-refractory disease and rapid fatal evolution. Biopsies confirmed the RLP with the presence of signet-ring cells (SRC) in a strong desmoplastic stromal reaction. However, the characteristic concentric ring pattern was absent. Instead, he had a large vegetative lesion with important tumor infiltration in mesorectum and pelvic organs, with major lymph node involvement. The 2 other patients presented resectable locally advanced disease with characteristic concentric ring pattern. No clinical and radiological responses were observed to neo-adjuvant chemoradiotherapy (CRT), including 1 patient with non-resectable disease at surgery and another with upstaged disease at pathological specimen after resection. However, data suggest 2 types of RLP: about half of patients are extremely sensitive to CRT with pathological complete response, and the other half are highly resistant with no response to CRT. Current data are insufficient to distinguish between these 2 populations.

CONCLUSIONS: The absence of a concentric ring pattern should not eliminate the suspicion of RLP, especially in young patients with aggressive clinical presentation. There are probably 2 types of RLP in terms of chemoradiosensitivity, and neoadjuvant CRT could delay the curative-intent surgery in refractory patients. Future molecular analysis of the tumor and its environment are required to characterize the 2 different forms of RLP to develop more personalized treatment strategies.