Potassium-secreting tumours of the large intestine

Endoscopic Submucosal Dissection of a Giant Rectal Adenoma Manifesting as McKittrick-Wheelock Syndrome

McKittrick-Wheelock syndrome (MKWS) is an uncommon clinical manifestation of large, villous, epithelial lesions of the distal colon and rectum. Excessive secretion of electrolyte-rich mucus from these lesions leads to secretory diarrhea, electrolyte disorders and acute renal failure. Several cases of MKWS have been reported since its initial description in 1954. The definitive treatment for the great majority of MKWS cases has consisted of surgical resection of the affected part of the colorectum, usually in the form of a low anterior resection or an abdominoperineal resection with the formation of an ostomy. Recent developments in endoscopic resection techniques now offer new, minimally invasive treatment alternatives for MKWS patients. We present the first reported case in the Western world of MKWS caused by a rectal adenoma with a size of 19 × 10 cm, treated through endoscopic submucosal dissection. Through the lessons learned by this case, as well as by a thorough review of the literature, we discuss this uncommon syndrome, focusing on treatment alternatives.

[Mckittrick-Wheelock syndrome as a rare manifestation of villous adenoma of the rectum]

McKittrick-Wheelock syndrome is a rare disease when villous adenoma of the distal colon predisposes to profuse watery diarrhea with subsequent severe electrolyte disturbances and acute renal damage. A differentiated approach to correct diagnosis requires in-depth pathophysiological knowledge of regulation of water-electrolyte metabolism, functional and organic disorders of gastrointestinal tract and clinical manifestations of hypoosmolar dehydration. The peculiarity of the McKittrick-Wheelock syndrome is a 100% probability of death without treatment and complete regression of symptoms under complex correction of homeostasis and total resection of tumor. We demonstrate the main clinical trends of the McKittrick-Wheelock syndrome. This report may be useful for general practitioners, gastroenterologists, oncologists, nephrologists and anesthesiologists.

McKittrick-Wheelock Syndrome: A Case Series

McKittrick-Wheelock syndrome is a rare and life-threatening disease characterized by the triad of (1) chronic mucous diarrhea, (2) renal function impairment with hydroelectrolyte imbalance, and (3) a giant colorectal tumor. Often, the tumor is a rectal adenoma. With the mortality being certain, if left untreated, it is important to raise awareness on the presentation, diagnosis, and management of this disease entity. Here, we presented 3 cases of McKittrick-Wheelock syndrome that were successfully managed with surgical resection at the Philippine General Hospital from August 2018 to May 2019. Resolution of their symptoms, reversal of their renal impairment, and correction of their electrolyte depletion were noted after removal of the tumor with a sphincter-saving operation.

A systematic review of McKittrick-Wheelock syndrome

INTRODUCTION

McKittrick-Wheelock syndrome describes the condition of extreme electrolyte and fluid depletion caused by large distal colorectal tumours, usually the benign villous adenoma. Patients generally present critically unwell with severe hyponatraemia, hypokalaemia and/or acute kidney injury.

METHODS

A structured literature review was undertaken to discover what is known about this condition, which is almost universally described as rare. Important features of the syndrome were identified, including common presenting symptoms, blood results, tumour location and size.

FINDINGS

Our literature search identified 257 cases reported across all languages. The most remarkable features were the long duration of symptoms (median 24 months) and the significant electrolyte derangements (median sodium of 122mmol/l and median potassium of 2.7mmol/l at initial presentation). Five key recommendations are made to improve diagnosis, including aggressive fluid resuscitation to match rectal losses and surgical intervention on the index admission. The advantages and disadvantages of different treatment options are discussed, including minimally invasive alternatives to traditional resectional surgery.

CONCLUSIONS

McKittrick-Wheelock syndrome describes a normally benign condition that can cause patients to become critically unwell and so it behoves all clinicians to be aware of it. By publishing recommendations based on a comprehensive literature review, we aim to improve diagnosis and management of this life threatening condition.

Pathophysiology of potassium absorption and secretion by the human intestine

When normal people ingest 90 mEq/day of K+ in their diet, they absorb about 90% of intake (81 mEq) and excrete an equivalent amount of K+ in the urine. Normal fecal K+ excretion averages about 9 mEq/day. The vast majority of intestinal K+ absorption occurs in the small intestine; the contribution of the normal colon to net K+ absorption and secretion is trivial. K+ is absorbed or secreted mainly by passive mechanisms; the rectum and perhaps the sigmoid colon have the capacity to actively secrete K+, but the quantitative and physiological significance of this active secretion is uncertain. Hyperaldosteronism increases fecal K+ excretion by about 3 mEq/day in people with otherwise normal intestinal tracts. Cation exchange resin by mouth can increase fecal K+ excretion to 40 mEq/day. The absorptive mechanisms of K+ are not disturbed by diarrhea per se, but fecal K+ losses are increased in diarrheal diseases by unabsorbed anions (which obligate K+), by electrochemical gradients secondary to active chloride secretion, and probably by secondary hyperaldosteronism. In diarrhea, total body K+ can be reduced by two mechanisms: loss of muscle mass because of malnutrition and reduced net absorption of K+; only the latter causes hypokalemia. Balance studies in patients with diarrhea are exceedingly rare, but available data emphasize an important role for dietary K+ intake, renal K+ excretion, and fecal K+ losses in determining whether or not a patient develops hypokalemia. The paradoxical negative K+ balance induced by ureterosigmoid anastomosis is described. The concept that fecal K+ excretion is markedly elevated in patients with uremia as an intestinal adaptation to prevent hyperkalemia is analyzed; we conclude that the data do not convincingly show the existence of a major intestinal adaptive response to chronic renal failure.

The renal concentrating defect associated with potassium depletion is independent of prostaglandin E2

Prostaglandin E2 (PGE2) impairs the hydrosmotic effect of vasopressin in toad bladder and mammalian kidney. Because some studies in animals have suggested that potassium depletion enhances renal PGE2 production, the present study examined whether the renal concentrating defect of potassium depletion in humans is mediated by PGE2. Five normal volunteers were studied before and after moderate potassium depletion achieved by 10 days of dietary potassium restriction and administration of a polystyrene sulfonate potassium exchange resin (Kayexalate). Maximal urinary osmolality (Umax) decreased from 1,094 +/- 58 (mean +/- SEM) to 820 +/- 26 mmol/kg (mOsm/kg) (P less than 0.01) following potassium depletion, but urinary PGE2 excretion did not change (496 +/- 145 and 435 +/- 186 ng/d, respectively). Indomethacin suppressed PGE2 excretion significantly, but failed to increase Umax in either the normal or the potassium-depleted state (1,094 +/- 34 and 825 +/- 56 mmol/kg, respectively). It is concluded that the renal concentrating defect produced by moderate potassium restriction in humans is not mediated by PGE2.

Cancer and the kidney: complications of neoplasms

Various renal complications occur during the course of neoplastic disease. The therapeutic and prognostic implications differ according to the reversibility of both the underlying malignancy and the superimposed complications in the kidney. Since the mechanisms of renal failure vary significantly in patients with different types of malignancy, it is essential to avoid generalizations about etiologic factors or likely outcomes of the disease processes. The pathophysiologic abnormalities should be determined in each patient, and the reversibility of both the neoplastic and problems assessed before therapeutic decisions are made. This often requires a team effort by the internist, oncologist, nephrologist, urologist and, most importantly, the patient.

Villous adenoma with hyponatremia and syncope: report of a case

A case of villous adenoma of the colon with hyponatremia, hypovolemia, and syncope is presented. The correct diagnosis was delayed because of the prevailing idea that villous adenomas are associated with hypokalemia. The patient recovered fully after surgical removal of one of the largest villous adenomas reported in the literature. Sodium loss may be the dominant feature of this syndrome. Villous adenoma has to be included among the causes of hyponatremia.

Villous adenoma of the colon with severe fluid and electrolyte depletion: report of a case

A case of severe fluid and electrolyte depletion resulting from a massive villous adenoma of the rectosigmoid colon is presented. The syndrome is discussed, and the often insidious presentation and life-threatening aspects are emphasized.

Villous adenomas of the colon and rectum

Our thirteen year experience with villous adenomas of the colon and rectum, embracing 264 patients, is reported. The average age of patients was sixty-two years with an almost equal sex distribution. Seventy-two per cent of the lesions occurred in the rectum and rectosigmoid and the most frequent symptoms were rectal bleeding and diarrhea. A positive correlation between size of adenoma and incidence of malignancy was noted. Although 55 per cent of the lesions were malignant, only 22 per cent harbored invasive carcinoma and only 10 per cent of the deaths were due to metastatic carcinoma. It is concluded that in the absence of invasive carcinoma, the clinical behavior of this tumor is relatively benign and a more conservative approach to the surgical management of this neoplasm should be encouraged.

Papillary adenomas of the colon and rectum: a twelve-year review

During a 12-year period, 185 patients with papillary adenomas of the colon and rectum were treated. The average age was 63 years and there was a 10 per cent female preponderance. Seventy-one per cent of the lesions occurred in the rectum and rectosigmoid, and 40 per cent of the patients had rectal bleeding. Fifty-two per cent of the lesions were malignant: however, only 9 per cent of the patients died with metastatic carcinoma. The five-year survival rate in patients with papillary adenocarcinoma was 75 per cent. The results of this review indicate that a conservative approach to the surgical management of papillary adenoma of the colon and rectum should be encouraged, unless the tumor contains or is suspected to contain invasive carcinoma.

Villous tumours of the rectum associated with severe fluid and electrolyte disturbance

Two cases of villous tumour of the rectum associated with severe electrolyte disturbance leading to renal failure are presented.

Evidence is produced to show that electrolyte loss is general rather than selective and certainly not confined to potassium.

The ratio of sodium to potassium lost in rectal fluid is of the order of 3–4 : 1.

Correction of sodium deficiency, acidosis, and hypovolaemia by the intravenous route is of paramount importance.

Total correction of potassium deficiency in this way is neither practicable nor necessary but particular care should be taken to maintain plasma potassium levels during correction of metabolic acidosis.

Operative removal of the tumour should await restoration of electrolyte and fluid balance.

Syndromes of water and electrolyte depletion of intestinal origin

Because of the important part played by the intestine in maintaining the constancy of the internal environment, any disturbance in the orderly sequence of secretion and reabsorption of water and electrolytes can quickly lead to severe fluid depletion. Malabsorption of water and electrolytes may occur in diseases of the intestinal mucosa or following massive resection of bowel or as a result of disordered intestinal motility. The handling of fluids by the bowel may be altered by the action of hormones or of bacterial toxins, or in the presence of neoplasms. Electrolyte disorders may result from the introduction of abnormal solutions into the intestinal lumen.

Management of the clinical problems requires a clear understanding of the abnormal mechanisms and urgent attention to the re-institution of water and salt balance, restoration of acid-base status and replacement of lost potassium.

A MUCUS-SECRETING VILLOUS ADENOMA OF THE RECTUM

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