Allen Mayer
^PK
March 1989
CLINICAL UTILITY OF SPECIAL STAINS FOR MICRO-ORGANISMS
IN BONE MARROW BIOPSIES
A retrospective study was initiated to evaluate the impact on patient
management of special stains for micro-organisms in bone marrow biopsies
at San Francisco General Hospital, an institution with a high prevalence of
HIV infection and AIDS. Thirty-six bone marrow specimens were submitted for
culture over a 20.5 month period. Three of these had neither AFBi^or fungal
special stains performed, two had fungal but not AFB stains done, and three
*had AFB, but not fungal, stains performed. The remainder had both special
stains performed.
Using culture as the gold standard for bone marrow infection, fungal
s p e c i a l s t a i n h a d a 1 0 0 % s e n s i t i v i t y a n d s p e c i fi c i t y ( F i g u r e l ) e A F B
s t a i n i n g h a d a n o v e r a l l s e n s i t i v i t y o f 4 1 % a n d a s p e c i fi c i t y o f 1 0 0 %
(Figure 2). When broken down between MTB and MAC, staining for MTB had
a sensitivity of 2/5, as compared to 5/12 for MAC. Of course, staining
{^' could not distinguish between MTB and MAC.
Clinical utilization of special stains varied with respect to the
micro-organism involved. In the two cases of disseminated histoplasmosis,
anti-fungal therapy was started on the basis of the H and E, and methenamine
s i l v e r, s t a i n i n g o f t h e b o n e m a r r o w. H o w e v e r, o n e c a s e h a d c u l t u r e s o f u r i n e ,
sputum, and blood from the month prior to the bone marrow biopsy procedure
w h i c h d i d g r o w o u t H i s t o p l a s m a . S i m i l a r l y, t h e t h r e e p a t i e n t s w h o w e r e s e e n
to have budding yeast indicative of Cryptococcus in their bone marrow
biopsies had already been diagnosed on the basis of CSF examination, but
in these cases therapy was started on the basis of the CSF and not the
bone marrow results.
In one of the seven patients positive for mycobacterium by special
stain in the bone marrow, the presence of AFB organisms confirmed the
validity of anti-mycobacterial therapy already started on clinical grounds.
M T B d i d g r o w o u t f r o m t h i s p a t i e n t ' s b o n e m a r r o w. A s e c o n d p a t i e n t a l s o
was started on therapy as a result of positive AFB special stain (pending
c u l t u r e i d e n t i fi c a t i o n ) , b u t M A C g r e w o u t i n t h i s c a s e . B o n e m a r r o w
special staining was duplicated in this patient by the detection of AFB
b y s p e c i a l s t a i n i n a n a s a l b i o p s y. I n c o n t r a s t t o t h e s e t w o p a t i e n t s , a
third patient's anti-mycobacterial therapy was discontinued as a result
of detection of AFB in the bone marrow by special stain. This AIDS patient
was being treated for disseminated MAC, as diagnosed by a prior blood culture,
Allen Mayer
March 1989
and continued presence of AFB organisms in the bone marrow with therapy
was interpreted as therapy failure.
In the remaining four of the seven patients positive for AFB by
s p e c i a l s t a i n , t h e r a p y w a s u n a f f e c t e d b y t h i s fi n d i n g . O n e p a t i e n t w a s p u t
o n t h e r a p y f o r p o s s i b l e m y c o b a c t e r i a l i n f e c t i o n a s a r e s u l t o f fi n d i n g
liver granuloma, and the bone marrow results were not noted in the chart.
MAC grew out from bone marrow, liver and blood cultures from this patient.
Another patient with a miliary picture on chest radiograph was put on therapy
' s e c o n d a r y t o fi n d i n g A F B i n s p u t u m s m e a r s . I n t h i s c a s e , t h e p o s i t i v e
acid fast special stain in the bone marrow did contribute to establishing
an AIDS diagnosis. This patient grew out MTB from sputum and bone marrow.
A third parient's positive AFB stain in his bone marrow was assumed to be MAC
since prior blood culture had grown out MAC, and therapy was not initiated.
A fourth patient had a bone marrow procedure done as an out-patient which
was positive for AFB by special stain, and which grew out MAC, but the
special stain results are not noted in the chart, and it is not clear
when anti-mycobacterial therapy was started.
In summary, therapeutic decisions were made as a direct consequence of
positive special stains for micro-organisms in bone marrow in 2/2 cases
o f h i s t o p l a s m o s i s , a n d 3 / 7 m y c o b a c t e r i u m c a s e s . H o w e v e r, i n o n e o f t h e
histoplasmosis cases and in one of the mycobacterium cases, the bone marrow
fi n d i n g s d u p l i c a t e d d e t e c t i o n o f t h e m i c r o - o r g a n i s m i n o t h e r t i s s u e s i t e s .
B o n e m a r r o w s p e c i a l s t a i n s d u p l i c a t e d d i a g n o s t i c fi n d i n g s i n o t h e r t i s s u e s
in one other mycobacterium case and in the three cryptococcus cases, but
i n t h e s e c a s e s t h e r a p y w a s b a s e d o n t h e fi n d i n g s i n t h e o t h e r t i s s u e s , a n d
t h e b o n e m a r r o w r e s u l t s d i d n o t d i r e c t l y p r o m p t o r a l t e r t h e r a p y. I t i s
of interest to note that in two cases, positive staining of AFB in the bone
marrow was assumed (correctly) to be MAC, and therapy was either not started,
o r d i s c o n t i n u e d , a s a r e s u l t o f t h e fi n d i n g .
A n o t h e r r e l a t e d q u e s t i o n i s w h e t h e r, i n c a s e s w h e r e s p e c i a l s t a i n s
were negative but bone marrow cultures did indeed grow out pathogens,
therapy was withheld as a result of the negative result, or were patients
treated appropriately on clinical grounds. In the seven patients who grew
out MAC from bone marrow but were negative by AFB stain, only one was started
empirically on anti-mycobacterial drugs= This patient did have a granuloma
i n t h e b o n e m a r r o w b i o p s y, b u t t h e c h a r t s a y s t h e r a p y w a s s t a r t e d o n t h e
basis of the chest radiograph. In the three patients who grew out MTB
but were negative by AFB stain, one patient was started on therapy two
*Jfl]P™efi!liy
Allen Mayer
March 1989
days before the bone marrow procedure on the basis of a positive AFB stain
in a lymph node aspirate. Another patient was started on therapy based
on clinical grounds, and granulomas in the bone marrow biopsy supported
t h i s e m p i r i c t h e r a p y. A t h i r d p a t i e n t d i e d a c u t e l y b e f o r e t h e r a p y w a s b e g u n ,
S o i n s u m m a r y, i f o n e i s o f t h e o p i n i o n t h a t M A C c a n n o t b e e ff e c t i v e l y
treated, then negative bone marrow AFB stains did not alter appropriate
therapy based on clinical suspicion and/or other diagnostic modalities.
A fi n a l q u e s t i o n t h a t c a n b e a d d r e s s e d i s t h e s e n s i t i v i t y o f
granulomas in these bone marrow biopsies. Six of twelve MAC-infected
bone marrows and four of five MTB-infected bone marrows had granulomas.
In two of five MAC-infected bone marrows with micro-organisms detected
by acid fast staining, granulomas were absent. In
contrast, both of the MTB-infected bone marrows showing positive AFB
s t a i n i n g a l s o h a d g r a n u l o m a s . Tw o o f t h r e e o f t h e M T B - i n f e c t e d b o n e
marrows that did not show AFB staining nevertheless had granulomas
( i n o n e o f t h e s e c a s e s t h e g r a n u l o m a s c o n fi r m e d t h e v a l i d i t y o f e m p i r i c
therapy as noted above), while three of seven of the MAC-infected bone
marrows negative by AFB staining were positive for granulomas. One of
these latter cases is notable for the absence of fungal organisms by
s p e c i a l s t a i n o r b y c u l t u r e g r o w t h f r o m t h e b o n e m a r r o w, y e t a b l o o d
culture obtained during the week prior to the bone marrow procedure did
eventually grow out histoplasma. Therapy in this patient was prompted by
t h e p o s i t i v e b l o o d c u l t u r e , a n d n o t t h e g r a n u l o m a i n t h e b o n e m a r r o w.
SUMMARY
Special stains were positive in 12 of 33 bone marrow biopsies reviewed. Positive
s p e c i a l s t a i n s p r o m p t e d , o r c o n fi r m e d e m p i r i c , t h e r a p y i n t w o
of these cases in the absence of diagnostic material from other
tissue sites. In six other cases, positive special stains duplicated
tissue diagnoses from other sites. Positive special stains in three
additional cases did not prompt therapy either through oversight
or active decision. In one case therapy was discontinued as a result
of a positive special stain.
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