Diagnosis and Reasoning
This patient's history has two important complaints: a lump in the right loin and multiple episodes of rectal bleeding.
The rectal bleeding is almost certainly due to a gastrointestinal (GI) lesion. The loin lump on the other hand could be due to a musculoskeletal, dermatological or even a renal lesion.
The question here is whether these complaints are due to a single pathology - or whether two unrelated pathologies are involved.
The next point of note is the recent rapid enlargement of the lump - a potentially sinister feature which warrants a meticulous physical examination.
Examination shows that the lump is most likely of muscular origin. In this context, the muscular tumors most likely to show a rapid enlargement are rhabdomyomas, desmoid tumours and rarely, fibromas.
The last (but not least) point of note is the presence of multiple polyps upon rectal examination - this is strongly suggestive of a GI polyposis syndrome. Further visualization of the GI tract via colonoscopy and upper GI endoscopy is mandatory.
Colonoscopy reveals the entire colon and rectum to be carpeted by polyps, while histology shows them to be tubular adenomas with varying degrees of dysplasia - confirming the presence of a colonic polyposis syndrome.
The CT scan confirms the muscular origin of the lump. However, an excision biopsy is needed to determine the exact nature of the tumor. Note that incision biopsy is contraindicated, as this will result in tumor seeding if the lump is malignant.
The polyposis syndromes most likely to give rise to a synchronous muscular lump are Familial Adenomatous Polyposis syndrome (FAP) and Gardner's syndrome (GS). Genetic analysis is required for further differentiation.
Note that prophylactic colectomy is indicated in both conditions, as is family screening. Steroids are not indicated.
This patient turned out to have GS, while the loin lump was found to be a desmoid tumor. Her treatment included restorative proctocolectomy and ileal pouch anal anastomosis (IPAA) as well as resection of the desmoid tumor.
GS is an autosomal dominant condition characterized by colonic polyps and extra-colonic manifestations such as osteomas and skin and soft tissue tumors. The annual incidence in the United States is one person per million individuals.
GS is a variant of familial adenomatous polyposis (FAP), and is caused by germ-line mutations in the adenomatous polyposis coli (APC) gene. The extra-colonic manifestations are typically more marked than in FAP.
Most patients have a family history of the condition, although up to a quarter of them may have a new mutation.
The main GI manifestations of GS include colonic, gastric and small intestinal adenomatous polyps, and peri-ampullary carcinomas.
Polyp formation usually commences at puberty and undergoes progressive malignant transformation, resulting in the development of colorectal carcinoma in almost 100% of patients by the fourth decade of life.
Osteomas appear in about half of patients and manifest earlier than polyposis. The vast majority are located on the skull, with the most commonly affected bones being the mandible and maxilla.
Desmoid tumors appear in a minority of patients, and are mostly located in the abdominal wall or intra-abdominally (especially in the mesentery). These may lead to potentially fatal complications such as obstruction, abscess formation, or constriction of vessels or ureters.
Patients with GS typically present with anemia, rectal bleeding, cramping abdominal pain, diarrhea, bowel obstruction and mucous discharge. Large polyps may prolapse through the anus, or give rise to intussusception or ileus.
Examination may show cutaneous signs such as epidermoid cysts, fibromas, lipomas, leimoyomas, neurofibromas and pigmented skin lesions. Fundoscopy may show multiple hyperpigmented patches due to congenital hypertrophy of the retinal pigmented epithelium (CHRPE).
Other manifestations of GS include papillary thyroid cancer; benign intracranial neoplasms such as meningiomas; hepatic, biliary and adrenal neoplasms; osteosarcomas; chondrosarcomas; and dental disorders.
The diagnosis of GS should be suspected in patients with a suggestive family history and/or clinical findings. Colonoscopy typically demonstrates multiple polyps (which are usually small, i.e. < 5 mm) throughout the colon. Definitive diagnosis requires genetic testing.
Prompt treatment is advised at diagnosis, as between a quarter to two-thirds of patients have already developed colorectal cancer, while the remainder will invariably undergo malignant transformation.
Key elements of the management include resection of the colon; treatment of extra-colonic manifestations; and screening of close relatives.
If at all possible, prophylactic colonic resection should be undertaken before 25 years of age (ideally between 16 to 20 years of age). Delay until the development of colorectal carcinoma results in a markedly worse prognosis.
The two main surgical options are colectomy with ileorectal anastamosis (IRA) and proctocolectomy with ileal pouch anal anastomosis (IPAA).
IRA is technically simpler, but is associated with a risk of delayed malignancy, as the rectal mucosa is retained. IPAA is more technically demanding and has a higher morbidity, but is associated with a survival rate of almost 100%, as no large intestinal epithelium remains.
Due to the risk of recurrence and increased risk of cancer of the other organs, it is essential to follow these patients up after surgery. This should include regular sigmoidoscopy and upper GI endoscopy, as well as thyroid surveillance.
As surgery results in considerable morbidity, there is intensive investigation for drugs that could decrease the malignant potential of the polyps.
Randomized trials have shown that the NSAIDS sulindac and celecoxib cause a significant reduction in adenomas, although complete regression does not occur.
Thus, while NSAIDS are not a replacement for surgery, they may be considered as an interim measure in mild disease, or in the treatment of recurrent polyps following surgery.
Considering extra-colonic manifestations, the treatment of cutaneous cysts and osteomas is similar to those in ordinary individuals, i.e. when symptomatic, or for cosmetic reasons. Treatment of desmoid tumors is recommended only in symptomatic patients, as recurrence is common.
Screening of the family members is an integral part of the management, with genetic testing being the most effective method for demonstrating the mutated APC gene. Relatives in whom the mutation is detected should undergo regular surveillance.
Take home messages
1. GS is a variant of FAP in which the extra-colonic manifestations are more prominent.
2. Up to a quarter of patients may have no family history of GS.
3. All patients with GS develop colorectal cancer if left untreated.
4. If GS is detected in the pre-malignant state, prophylactic colectomy should be performed.
5. Screening of all close relatives is mandatory.
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