Diarrhea - Case 17-4: 15-Month-Old Boy
Diarrhea - Case 17-4: 15-Month-Old Boy: Excerpt from Pediatric Complaints and Diagnostic Dilemmas
I. History of Present Illness
A 15-month-old boy presented with a 3-month history of watery diarrhea
associated with weight loss. At 12 months of age, he developed diarrhea
characterized by six to eight watery brown stools per day accompanied by
significant flatulence. There was no associated emesis or blood in the stool.
He had continued to have a good appetite despite the frequent stooling. Dietary
changes, including a BRAT (bananas, rice, apples, toast) diet and a
lactose-free diet, had been introduced but did not improve the diarrhea.
Occasional low-grade fevers had been noted. There was no history of foreign
travel or ill contacts. There were two cats and one dog in the home. He had
lost 3 pounds in the last 3 months.
II. Past Medical History
He was a full-term infant with a birth weight of 6 lb, 11 oz who was fed Similac
without any problems. He had normal weight gain and developmental milestones.
He had been introduced to rice cereal, baby foods, and adult table foods
without any problems. He was taking no medications.
III. Physical Examination
T, 36.8°C; RR, 26/min; HR, 100 bpm; BP, 102/53 mm Hg
Weight, less than 5th percentile (50th percentile for a 6-month-old child);
height, 10th percentile
The initial examination revealed a quiet, gaunt-appearing child. His eyes were
sunken, but the rest of the head, eyes, ears, nose, mouth, and throat
examination was unremarkable. His cardiac and respiratory examinations were
normal. His abdominal examination revealed no masses. His liver edge was
palpable at the right costal margin. There was no clubbing of the fingers. He
had dry skin around his nose and lips. He had very little subcutaneous fat. His
neurologic examination was nonfocal.
IV. Diagnostic Studies
Laboratory analysis revealed 11,100 WBCs/mm3 with 29% segmented neutrophils, 66% lymphocytes, and 5% monocytes. The
hemoglobin was 12.2 g/dL, and there were 492,000 platelets/mm
3. Electrolytes were significant for a potassium concentration of 2.8 mmol/L and
a bicarbonate concentration 16 mmol/L. His ESR was 4 mm/hour. Urinalysis was
negative, with a urine specific gravity of 1.005. The serum alkaline
phosphatase level was low at 115 U/L, whereas ALT was elevated at 59 U/L, AST
at 64 U/L, and lactate dehydrogenase at 845 U/L.
V. Course of Illness
The patient was admitted and hyperalimentation was started for his nutritional
status and to correct his hypokalemia. Blood culture and stool culture were
both negative. A sweat test was normal. A stool sample tested negative for
C. difficile toxins. Stool for ova and parasites revealed Indian meal moth larvae.
Colonoscopy was performed on the sixth day of hospitalization and revealed
nonspecific lymphoid hyperplasia. Despite taking nothing by mouth, he continued
to have mucusy diarrhea which became heme positive. Stool osmolality was normal
at 298 mOsm/kg H
2O. Chest radiography (Fig. 17-3) suggested a diagnosis, which was confirmed by
biopsy.
Discussion: Case 17-4
I. Differential Diagnosis
The chronic nature of his diarrhea for the last 3 months, associated with weight
loss, moved the differential diagnosis away from the diagnosis of acute
infectious diarrhea due to either bacterial or viral causes. A prolonged bout
of postinfectious diarrhea due to disaccharidase deficiency was possible but
unlikely. Chronic diarrhea due to infection with
C. difficile or ova and parasites was a possibility even without a history of antibiotic
use, bloody diarrhea, foreign travel, or use of untreated water sources. The
key observation in making this diagnosis occurred while the patient was in the
hospital: he took nothing by mouth but continued to produce profuse voluminous
watery diarrhea. This finding indicated the presence of secretory, rather than
osmotic, diarrhea. In this differential diagnosis, the list is rather brief and
includes rare congenital and paraneoplastic conditions. Congenital defects in
chloride or sodium transport are more likely to manifest in infancy. Infectious
causes of secretory diarrhea include small-bowel overgrowth or infection with
immuno adherent
E. coli stimulating gastrointestinal secretions. Any cause of villous atrophy, whether
congenital, autoimmune, or secondary to immune deficiency (e.g., HIV infection,
severe combined immunodeficiency) may also result in this presentation.
Neuroblastoma or other tumors of neural crest origin (e.g., ganglioneuroma) may
secrete vasoactive intestinal peptide (VIP), resulting in secretory diarrhea.
II. Diagnosis
Chest radiography revealed a large posterior mediastinal mass (Fig. 17-3).
Computed tomography of the chest performed on the seventh day of
hospitalization confirmed a 4
× 4 cm right posterior mediastinal mass. The urine vanillylmandelic acid level
was 498 mg/g of creatinine, and the homovanillic acid level was 245 mg/g of
creatinine, both extremely elevated. Surgical excision revealed neuroblastoma
with a favorable histology.
These findings were consistent with the diagnosis of neuroblastoma causing
secretory diarrhea.
III. Incidence and Epidemiology
The annual incidence of neuroblastoma is approximately 8 per 1 million children
younger than 15 years of age. The median age at diagnosis is 22 months, and 95%
of cases are diagnosed by the age of 10 years. Neuroblastoma accounts for
approximately 6% of all pediatric tumors. There is a slight male preponderance,
with a ratio of 1.2:1. There also appear to be cases that are familial in
nature and manifest at a younger age, with a median age of 9 months at
diagnosis. These tumors derive from postganglionic sympathetic cells found in
the paraspinal sympathetic ganglia and in the adrenal chromaffin cells.
Neuroblastoma and ganglioneuroblastoma represent the malignant forms of these
neural crest tumors, whereas ganglioneuroma represents the most benign form,
with no metastatic potential.
IV. Clinical Presentation
Most pediatric patients with neuroblastoma are diagnosed by 5 years of age, and
most tumors are intraabdominal in location. However, patients older than 1 year
of age have a higher incidence of intrathoracic and cervical tumors, compared
with younger patients. Among children older than 1 year of age, 75% present
with a disseminated, advanced stage of disease and account for a significant
proportion of neuroblastoma-associated mortality. Infants younger than 1 year
of age tend to present with lower-stage disease and have much higher cure
rates. Some of the tumors in this latter group even undergo spontaneous
regression. One percent of patients have no detectable primary tumor. In 35% of
children, neuroblastoma metastases occur to the regional lymph nodes,
qualifying as disseminated disease. Hematogenous spread to bone, bone marrow,
liver, and skin also occurs. Late metastases are seen in the brain and lung.
Patients may present with a large abdominal mass or with respiratory distress
secondary to the intraabdominal mass. Intrathoracic tumors are often
incidentally found. Opsoclonus-myoclonus is an well-defined presenting syndrome
for neuroblastoma. Presentation as severe secretory diarrhea, as in this case,
is known as Verner-Morrison syndrome.
V. Diagnostic Approach
Clinical observation. The observation of continued, intractable watery diarrhea while the patient
takes nothing by mouth is key to the ultimate diagnosis. Whether this is
accomplished by obtaining a very thorough history or by observation while in
the hospital, this piece of information is vital to making the ultimate
diagnosis.
Radiography. Radiographs may localize calcifications, and often they provide the first
indication of the presence of a tumor as an incidental finding. Skeletal
surveys may show bone involvement and are used in tumor staging.
Computed tomography or magnetic resonance imaging. Three-dimensional imaging more accurately delineates the location of the tumor,
which is usually retroperitoneal or adrenal, and also assists in staging.
Occasionally, tumors are found along the sympathetic chain in the thoracic or
cervical region.
Vasoactive intestinal peptide level. Plasma VIP may be elaborated by tumors of neural crest origin and may cause
secretory diarrhea.
Urinary (or serum) catecholamine levels. Elevation of urinary homovanillic or vanillylmandelic acid, in conjunction with
diagnostic pathologic features, is diagnostic for neuroblastoma. These levels
may also be used to monitor disease activity.
Surgical removal. Complete surgical excision provides a pathologic specimen for further identification and characterization of the tumor and is also
therapeutic, especially with regard to the secretory diarrhea. It is also
important in the staging process, especially in assessing lymph node
involvement.
Bone scintigraphy. A bone scan is important in detecting possible metastases and is used in the
staging process.
Radionuclide scan. Radiolabeled metaiodobenzylguanidine (MIBG) is taken up by
catecholamine-secreting cells and is useful for staging (i.e., detecting bone
and soft tissue involvement).
VI. Treatment
Surgical resection is usually performed. Low-risk patients may not need any
additional therapy. Radiotherapy and chemotherapy are used, depending on the
stage of the disease. Patients with high-risk disease may have some improvement
in short-term survival with autologous bone marrow transplantation, but
longer-term outcome is still poor. Surgical removal of the tumor usually cures
the secretory diarrhea. The use of somatostatin analogues also has a
therapeutic effect on the secretory diarrhea, but the definitive therapy for
the diarrhea remains surgical.
VII. References
1. Castleberry R. Biology and treatment of neuroblastoma. Pediatr Clin North Am 1997;44:919–937.
2. Bown N. Neuroblastoma tumour genetics: clinical and biological aspects. J Clin Pathol 2001;54:897–910.
3. Castleberry R. Paediatric update: neuroblastoma. Eur J Cancer 1997;33:1430–1438.
4. Alexander F. Neuroblastoma. Urol Clin North Am 2000;27:383–392.
Pictures
Book Source Details
- Book Title: Pediatric Complaints and Diagnostic Dilemmas
- Author(s): Samir S Shah MD; Stephen Ludwig MD
- Year of Publication: 2003
- Copyright Details: Pediatric Complaints and Diagnostic Dilemmas, Copyright © 2003 Lippincott Williams & Wilkins.
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