Background: Lynch Syndrome (LS) is a familial cancer condition caused by germline mutations in DNA mismatch repair genes. Individuals with LS have a greatly increased risk of developing colorectal cancer (CRC) and it is therefore important to identify mutation carriers so they can undergo regular surveillance. Tumor DNA from LS patients characteristically shows microsatellite instability (MSI). Our aim here was to screen young CRC patients for MSI as a first step in the identification of unrecognized cases of LS in the Saudi population. Materials and Methods: Archival tumor tissue was obtained from 284 CRC patients treated at 4 institutes in Dammam and Riyadh between 2006 and 2015 and aged less than 60 years at diagnosis. MSI screening was performed using the BAT-26 microsatellite marker and positive cases confirmed using the pentaplex MSI analysis system. Positive cases were screened for BRAF mutations to exclude sporadic CRC and were evaluated for loss of expression of 4 DNA mismatch repair proteins using immunohistochemistry. Results: MSI was found in 33/284 (11.6%) cases, of which only one showed a BRAF mutation. Saudi MSI cases showed similar instability in the BAT-26 and BAT-25 markers to Australian MSI cases, but significantly lower frequencies of instability in 3 other microsatellite markers. Conclusions: MSI screening of young Saudi CRC patients reveals that approximately 1 in 9 are candidates for LS. Patients with MSI are strongly recommended to undergo genetic counselling and germline mutation testing for LS. Other affected family members can then be identified and offered regular surveillance for early detection of LS-associated cancers.

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Introduction: Macrodystrophia lipomatosa is a rare benign condition characterized by a progressive persistent proliferation of the mesenchymal components and elements, with a disproportionate increase in fibro-adipose tissue. It causes a debilitating functional and psychological effect on the patient and his family. Case presentation: A 25-years-old male patient presented complaining of left middle finger swelling which was painless and progressive in size with no restriction of range of motion. Plain X-ray films of the left hand showed a heterogeneous lobulated soft tissue mass on the volar aspect of the middle finger which was confirmed by MRI scan. Surgery was performed by doing a left middle finger soft tissue excision and diagnosis of Macrodystrophia lipomatosa was confirmed by the histopathology report. Patient was on regular follow up in the clinic with no tumour recurrence and an excellent cosmetic as well as functional result with full finger joints range of motion. Conclusion: Macrodystrophia lipomatosa should be suspected with this kind of presentations. Combination of the clinical history and examination with the aid of radiological assays aided in the diagnosis of this extremely rare case and led to the appropriate management by excising this mass and restoring the normal function of the patient’s hand.