31

CASE 31


RR, a 17-year-old woman who was previously well, has been admitted to the hospital because of fever, rash, generalized fatigue, and acute pain in the left eye. In the last 2 months she has lost 12 kg in weight and reports an intermittent fever with fatigue of the same duration. She has had multiple sexual partners and a therapeutic abortion at 14 years of age. There has been no recent travel, and a tuberculosis skin test is negative (with positive control). She appears ill, has marked conjunctival infection, a tender sclera with palpation, and left retinal detachment with some peri-orbital swelling. Fundoscopic/ophthalmoscopic examination (of the optic disc, blood vessels, and retina) is otherwise normal. The remainder of the ears, nose, and throat examination is unremarkable, although she does have prominent nontender cervical nodes. There is also swelling of the inguinal nodes, a macular rash (small, flat spots) on the thigh, and a faint cardiac murmur in the upper chest.


An HIV (ELISA) and a syphilis (VDRL) test were ordered immediately, as was a urine and blood screen culture, and chest radiograph. HIV tests were negative, but a serologic test for syphilis was positive, although a hemagglutination test for Treponema pallidum was negative (i.e., a “false positive” syphilis test was seen). Urine showed 2+ (30 mg/dL) protein, some red blood cells, and some hyaline casts (generally reflecting inflammatory changes in the upper urinary tract, including the kidney). Blood screen indicated that she was moderately anemic (hemoglobin 80% of normal; see Appendix for reference value), with a lymphopenia (lymphocyte counts about 20% of normal) and low platelets. The chest radiograph was normal. A bone marrow aspirate with smear was performed. However, there was no evidence for lymphoma or leukemia, Hodgkin’s disease, malignant histiocytosis (resident macrophages in connective tissue), or other immunolymphoproliferative disorders. Computed tomography (CT) showed swelling of the soft tissues around the left eye and evidence for cerebral atrophy. Blood cultures remained negative throughout hospitalization.



QUESTIONS FOR GROUP DISCUSSION



1. This clinical picture is consistent with multiple different disorders. So, the challenge is to exclude disorders by the judicious use of tests. Review the results of each of the following tests and the conclusions that could be drawn on the basis of these results.
(a) Complete blood cell count

(b) Urinalysis

(c) Bone marrow aspirate and smear

(d) Culture

(e) Chest radiograph

(f) Computed tomography (CT)

(g) Antibody titer for HIV

(h) Antibody titer for syphilis

2. The serologic test for syphilis (VDRL) was positive. Yet the confirmatory test (hemagglutination assay) was negative. Explain.

3. The CT scan showed evidence for cerebral atrophy. In addition, laboratory tests revealed lymphopenia and thrombocytopenia. These results coupled with the cardiac murmur, a macular rash, and a positive syphilis VDRL are consistent with an autoimmune disorder. Explain why you would consider or rule out each of the following:
(a) Reiter’s syndrome

(b) Crohn’s disease

(c) sarcoidosis

(d) Behçet’s disease

(e) rheumatoid arthritis

(f) polyarteritis

(g) Wegener’s granulomatosis

(h) systemic lupus erythematosus

4. What result would you expect if you were to test for each of the following?
(a) antinuclear antibodies

(b) anti-dsDNA antibodies

(c) complement C3 or C4 levels

(d) biopsy of the rash

5. What therapy would you recommend? Explain.


RECOMMENDED APPROACH



Implications/Analysis of Family History


No family history is provided. See Cases 18 and 22 for genetics of this disorder.



Implications/Analysis of Clinical History


This presentation is consistent with multiple disorders; and in attempting to exclude them, it is essential to be judicious in choice of tests. The picture seems to be one of an acute disorder, and our diagnostic decision tree should keep this in mind.



Implications/Analysis of Laboratory Investigation



Ruling Out Infection


Early testing ruled out the probability of acute or chronic infectious disorders as explanation for these symptoms in that the chest radiograph is normal, blood cultures are negative, as are the tests for HIV and syphilis. Although the VDRL assay, the screening test for syphilis, was positive, the confirmatory test was negative. The VDRL assay detects anticardiolipid antibodies. Because these antibodies may be present in patients with some viral, bacterial, and parasitic infections, and in some autoimmune disorders, there is a high incidence of false-positive findings. Therefore, a confirmatory test that detects antibodies specific for antigens expressed on Treponema pallidum (the causative agent of syphilis) is required. The confirmatory test was negative, indicating that RR did not have syphilis, but she does have anticardiolipin antibodies, and we must take this into consideration when determining a diagnosis.



Ruling Out Malignancy


The likelihood of a malignancy (lymphoma, leukemia, Hodgkin’s disease, malignant histiocytosis, or other lymphoproliferative disorders) has lessened at this time in that the chest radiograph is normal and the white blood cell count is reduced (not elevated). As well, the bone marrow smear, which provides (1) a leukocyte estimate, (2) leukocyte differential, (3) the presence of abnormal cells (e.g., Reed-Sternberg cells in Hodgkin’s disease), (4) as well as erythrocyte, and (5) platelet morphology, was normal.



Anemia, Proteinuria, and Hyaline Casts


RR is moderately anemic, but a number of mechanisms can lead to anemia (e.g., trauma, autoanti-bodies, infections, iron deficiency, drug associated). Urinalysis revealed proteins, red blood cells, and hyaline casts. Hyaline casts consist of material shed from renal tubules but retain the shape of the tubule. Hyaline casts are made of gelled protein and are translucent.


The presence of protein, red blood cells, and hyaline casts in the urine is an indication that the kidneys are not functioning normally. Renal problems can develop as a result of immune complex deposition in the glomeruli. Because we have already ruled out an acute or chronic infection, as well as a malignancy, these could not be the source of antigen and so we should be focusing our attention to autoimmune disorders in which immune complexes contribute to the pathology. Circulating immune complexes could also trigger inflammatory reactions that result in swelling of soft tissues around the left eye and cerebral atrophy (as shown on CT).

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Jun 18, 2016 | Posted by in IMMUNOLOGY | Comments Off on 31

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