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343
Case Report
Imaging Findings Myopathy Arthur
M. A. De Schepper1
and
in a Patient Hendrik
with Pentazocine-Induced
R. M. Degryse
Fibrous myopathy is a well-known complication of repeated intramuscular injections of pentazocine, a commonly used analgesic drug. Indifference of the patients to and their silence about this indolent but frequently mutilating process are probably responsible for the paucity of reports and the lack of recognition of this entity. Fibrous myopathy has to be differentiated from neoplastic, infectious, traumatic, and dystrophic muscular disease. Few reports have been published on the imaging of pentazocine myopathy. We present a patient in whom
plain
film,
sonography,
CT,
and
MR
were
performed.
in both vious
quadriceps because
muscles.
of
peripheral
The radiolucencies contrast
became
enhancement
(Fig.
more
ob-
iC).
The
bilateral and multifocal appearance and the pleomorphic character of the lesions, together with a lack of clinical or biochemical signs of inflammation, made a neoplastic or inflammatory process unlikely. Further questioning revealed that the patient had been abusing intramuscular pentazocine via thigh injections. The injections stopped 8 months before the radiographic studies. The examination was
completed
with an MR scan and percutaneous
biopsy was performed on demand cancerphobia of the patient.
of the clinician
needle biopsy.
The
and to relieve
the
On transverse, Ti -weighted, spin-echo MR images (550/22, TR/ TE), signal intensity of the left quadriceps muscle was less homogeCase
Report
neous
A 35-year-old woman had a 2-month history of progressive, painless stiffening and enlargement of the left quadriceps muscle. The patient was the wife of a general practitioner. Physical examination showed a “rock-hard” induration ventrally in the thigh. The patient did
not
have
Laboratory tion
rate
history tests
(37
of or clinical
revealed
only
evidence an increased
for
systemic
myopathy.
erythrocyte
sedimenta-
sonography,
an inhomogeneous,
cification
was
muscles
(Fig. 1A). An unenhanced
numerous
seen
in the
calcifications
vastus
and
hypoechoic
mass
intermedius
and
ill-defined
small, linear muscle. On
with the
central
rectus
CT scan of both thighs hypolucencies
ceps muscles, most obvious on the left side. and vastus intermedius muscle were slightly cutaneous fat appeared normal (Fig. 1 B). A scan of both thighs showed multiple ill-defined
in both
cal-
femoris
revealed
on the right
side,
with
several
in the rectus femoris
ill-defined
areas
and vastus
of
lateralis
adequate tion.
sample
Unfortunately,
to
the
a hard, was the
prior
injections
boardlike
mass
collected
and
sample
allowed
(Fig.
1 E).
On
was punctured sent
for
microscopic
no further
percutaneous
and only one examina-
characterization
of
the lesion. The patient refused a second biopsy, but clinical examination after 3 and 6 months showed a gradual regression of the initial
induration
and tumefaction.
quadri-
The left rectus femonis enlarged, and the subcontrast-enhanced CT areas of enhancement
Discussion
Pentazocine is a commonly used neous abnormalities (woody infiltration,
Wilrijkstraat
AJR 154:343-344,
Roentgen
1990 0361-803X/90/1542-0343
related
biopsy,
needle
Received July 31 . 1 989; accepted after revision September 28, 1989. 1 Both authors: Department of Radiology, University Hospital Antwerp, Schepper. February
that
signal intensity
muscle, probably representing muscular atrophy with fatty replacement or possibly some residual proteinaceous fluid (Fig. i D). On coronal, T2-weighted, spin-echo images (2000/90), several poorly circumscribed areas of high signal intensity were seen within the quadriceps muscle, representing areas of fatty degeneration or cystic necrosis
mm/hr).
The initial plain film of the thigh showed numerous, and rounded calcifications in the region of the quadriceps
than
increased
© American
1 0, B-2520 Ray Society
Edegem,
Belgium.
Address
analgesic drug. Cutadeep ulcers, abnormal
reprint
requests
to A. M. A. De
Downloaded from www.ajronline.org by 112.26.80.145 on 10/13/15 from IP address 112.26.80.145. Copyright ARRS. For personal use only; all rights reserved
344
DE
SCHEPPER
AND
DEGRYSE
AJR:154, February 1990
Fig. 1.-A, Sonogram of left thigh shows inhomogeneous, hypoechoic mass (white arrowheads) with central calcification (curved arrow) in quadriceps region. B, Unenhanced CT scan of both thighs shows rounded calcifications (open arrow) and ill-defined hypolucencies in both quadriceps muscles (solid arrows). Note enlargement of left quadriceps muscle. C, CT scan after IV injection of iodinated contrast material. Note multiple ill-defined areas of (mostiy peripheral) contrast enhancement in both quadnceps muscles. D, Ti-weighted transverse MR image shows ill-defined areas of increased signal intensity, more obvious on left side (arrowheads). E, T2-weighted coronal MR image shows pooriy circumscribed areas of increased signal intensity more obvious on left side.
pigmentation, and lack of pain) and symmetrical myopathy have been reported in association with frequent superficial intramuscular injections [1 -3]. Clinically, these patients present with fibrotic induration of the injected muscles, limitation of motion due to muscle contraction and secondary joint contraction, minimal weakness, and neuropathic symptoms. Possible causes oflocalized myopathy are trauma of repeated injections, foreign body reaction, ischemia, and crystallization of the drug [1 3]. Secondary contraction and neuropathic disorders are explained by nerve damage and entrapment reflex sympathetic dystrophy [3-5]. Some authors suggest a systemic myotoxic effect of pentazocine, reporting cases of symmetrical contractions in all four extremities unrelated to the injected muscle [4] and even cases of myopathy after long-standing oral administration of pentazocine [6]. Focal muscle induration and fibrosis were not present in these cases, suggesting a different disease. The daily dose that can produce cutaneous and muscular complications is between 60 and 240 mg. The duration of the administration varies between 2 weeks and 3 years [5]. Animal experiments only partially explain the causal nelationship between pentazocine injections and myopathy [1]. Histologically, a diffuse fibrotic replacement of muscle fibers, a variable amount of inflammatory infiltrates, and rarely, small vessel thrombosis are described. The presence of birefningent crystals has been noted in areas of induration [7]. Diffuse soft-tissue and muscle calcifications are the only findings described on plain radiography [2, 5]. Sonognaphy ,
allows demonstration of the lesions, but lacks specificity. The bilateral and multifocal presentation together with the pleomorphic appearance on CT and MR caused by a mixture of fibrosis, fatty degeneration and cystic necrosis, calcifications, and a variable degree of inflammation are helpful in differentiating drug-induced myopathy from neoplastic, infectious, autoimmune, neurogenic, and other traumatic muscular injunies. Early recognition may be important in order to avoid further invasive diagnostic procedures and is mandatory to prevent irreversible muscular damage and subsequent neurologic complications.
REFERENCES 1 . Oh SJ, Rollins JL, Lewis I. Pentazocine-induced fibrous myopathy. JAMA 1975;231 :271-273 2. de Lateur BJ, Halliday WA. Pentazocine fibrous myopathy: report of two cases and literature review. Arch Phys Med Rehabil 1978;59:394-397 3. Levin BE, Engel WK. latrogenic muscle fibrosis. JAMA 1973;234:621-624 4. Roberson JA, Dimon JH. Myofibrosis and joint contractures caused by injections of pentazocine. J Bone Joint Surg [Am] 1983;65-A: 1007-1009 5. Hertzman A, Tcone E, Resnik CS. Pentazocine induced myocutaneous sclerosis. J Rheumatol i986;1 3:210-214 6. Frazier L, Neelon FA. Muscle stiffness and oral pentazocine. Arch Intern Med 1984;144: 1897-1 898 7. Adams EM, Horowitz HW, Sundstrom WA. Fibrous myopathy in association with pentazocine. Arch Intern Med 1983;143:2203-2204
343
Case Report
Imaging Findings Myopathy Arthur
M. A. De Schepper1
and
in a Patient Hendrik
with Pentazocine-Induced
R. M. Degryse
Fibrous myopathy is a well-known complication of repeated intramuscular injections of pentazocine, a commonly used analgesic drug. Indifference of the patients to and their silence about this indolent but frequently mutilating process are probably responsible for the paucity of reports and the lack of recognition of this entity. Fibrous myopathy has to be differentiated from neoplastic, infectious, traumatic, and dystrophic muscular disease. Few reports have been published on the imaging of pentazocine myopathy. We present a patient in whom
plain
film,
sonography,
CT,
and
MR
were
performed.
in both vious
quadriceps because
muscles.
of
peripheral
The radiolucencies contrast
became
enhancement
(Fig.
more
ob-
iC).
The
bilateral and multifocal appearance and the pleomorphic character of the lesions, together with a lack of clinical or biochemical signs of inflammation, made a neoplastic or inflammatory process unlikely. Further questioning revealed that the patient had been abusing intramuscular pentazocine via thigh injections. The injections stopped 8 months before the radiographic studies. The examination was
completed
with an MR scan and percutaneous
biopsy was performed on demand cancerphobia of the patient.
of the clinician
needle biopsy.
The
and to relieve
the
On transverse, Ti -weighted, spin-echo MR images (550/22, TR/ TE), signal intensity of the left quadriceps muscle was less homogeCase
Report
neous
A 35-year-old woman had a 2-month history of progressive, painless stiffening and enlargement of the left quadriceps muscle. The patient was the wife of a general practitioner. Physical examination showed a “rock-hard” induration ventrally in the thigh. The patient did
not
have
Laboratory tion
rate
history tests
(37
of or clinical
revealed
only
evidence an increased
for
systemic
myopathy.
erythrocyte
sedimenta-
sonography,
an inhomogeneous,
cification
was
muscles
(Fig. 1A). An unenhanced
numerous
seen
in the
calcifications
vastus
and
hypoechoic
mass
intermedius
and
ill-defined
small, linear muscle. On
with the
central
rectus
CT scan of both thighs hypolucencies
ceps muscles, most obvious on the left side. and vastus intermedius muscle were slightly cutaneous fat appeared normal (Fig. 1 B). A scan of both thighs showed multiple ill-defined
in both
cal-
femoris
revealed
on the right
side,
with
several
in the rectus femoris
ill-defined
areas
and vastus
of
lateralis
adequate tion.
sample
Unfortunately,
to
the
a hard, was the
prior
injections
boardlike
mass
collected
and
sample
allowed
(Fig.
1 E).
On
was punctured sent
for
microscopic
no further
percutaneous
and only one examina-
characterization
of
the lesion. The patient refused a second biopsy, but clinical examination after 3 and 6 months showed a gradual regression of the initial
induration
and tumefaction.
quadri-
The left rectus femonis enlarged, and the subcontrast-enhanced CT areas of enhancement
Discussion
Pentazocine is a commonly used neous abnormalities (woody infiltration,
Wilrijkstraat
AJR 154:343-344,
Roentgen
1990 0361-803X/90/1542-0343
related
biopsy,
needle
Received July 31 . 1 989; accepted after revision September 28, 1989. 1 Both authors: Department of Radiology, University Hospital Antwerp, Schepper. February
that
signal intensity
muscle, probably representing muscular atrophy with fatty replacement or possibly some residual proteinaceous fluid (Fig. i D). On coronal, T2-weighted, spin-echo images (2000/90), several poorly circumscribed areas of high signal intensity were seen within the quadriceps muscle, representing areas of fatty degeneration or cystic necrosis
mm/hr).
The initial plain film of the thigh showed numerous, and rounded calcifications in the region of the quadriceps
than
increased
© American
1 0, B-2520 Ray Society
Edegem,
Belgium.
Address
analgesic drug. Cutadeep ulcers, abnormal
reprint
requests
to A. M. A. De
Downloaded from www.ajronline.org by 112.26.80.145 on 10/13/15 from IP address 112.26.80.145. Copyright ARRS. For personal use only; all rights reserved
344
DE
SCHEPPER
AND
DEGRYSE
AJR:154, February 1990
Fig. 1.-A, Sonogram of left thigh shows inhomogeneous, hypoechoic mass (white arrowheads) with central calcification (curved arrow) in quadriceps region. B, Unenhanced CT scan of both thighs shows rounded calcifications (open arrow) and ill-defined hypolucencies in both quadriceps muscles (solid arrows). Note enlargement of left quadriceps muscle. C, CT scan after IV injection of iodinated contrast material. Note multiple ill-defined areas of (mostiy peripheral) contrast enhancement in both quadnceps muscles. D, Ti-weighted transverse MR image shows ill-defined areas of increased signal intensity, more obvious on left side (arrowheads). E, T2-weighted coronal MR image shows pooriy circumscribed areas of increased signal intensity more obvious on left side.
pigmentation, and lack of pain) and symmetrical myopathy have been reported in association with frequent superficial intramuscular injections [1 -3]. Clinically, these patients present with fibrotic induration of the injected muscles, limitation of motion due to muscle contraction and secondary joint contraction, minimal weakness, and neuropathic symptoms. Possible causes oflocalized myopathy are trauma of repeated injections, foreign body reaction, ischemia, and crystallization of the drug [1 3]. Secondary contraction and neuropathic disorders are explained by nerve damage and entrapment reflex sympathetic dystrophy [3-5]. Some authors suggest a systemic myotoxic effect of pentazocine, reporting cases of symmetrical contractions in all four extremities unrelated to the injected muscle [4] and even cases of myopathy after long-standing oral administration of pentazocine [6]. Focal muscle induration and fibrosis were not present in these cases, suggesting a different disease. The daily dose that can produce cutaneous and muscular complications is between 60 and 240 mg. The duration of the administration varies between 2 weeks and 3 years [5]. Animal experiments only partially explain the causal nelationship between pentazocine injections and myopathy [1]. Histologically, a diffuse fibrotic replacement of muscle fibers, a variable amount of inflammatory infiltrates, and rarely, small vessel thrombosis are described. The presence of birefningent crystals has been noted in areas of induration [7]. Diffuse soft-tissue and muscle calcifications are the only findings described on plain radiography [2, 5]. Sonognaphy ,
allows demonstration of the lesions, but lacks specificity. The bilateral and multifocal presentation together with the pleomorphic appearance on CT and MR caused by a mixture of fibrosis, fatty degeneration and cystic necrosis, calcifications, and a variable degree of inflammation are helpful in differentiating drug-induced myopathy from neoplastic, infectious, autoimmune, neurogenic, and other traumatic muscular injunies. Early recognition may be important in order to avoid further invasive diagnostic procedures and is mandatory to prevent irreversible muscular damage and subsequent neurologic complications.
REFERENCES 1 . Oh SJ, Rollins JL, Lewis I. Pentazocine-induced fibrous myopathy. JAMA 1975;231 :271-273 2. de Lateur BJ, Halliday WA. Pentazocine fibrous myopathy: report of two cases and literature review. Arch Phys Med Rehabil 1978;59:394-397 3. Levin BE, Engel WK. latrogenic muscle fibrosis. JAMA 1973;234:621-624 4. Roberson JA, Dimon JH. Myofibrosis and joint contractures caused by injections of pentazocine. J Bone Joint Surg [Am] 1983;65-A: 1007-1009 5. Hertzman A, Tcone E, Resnik CS. Pentazocine induced myocutaneous sclerosis. J Rheumatol i986;1 3:210-214 6. Frazier L, Neelon FA. Muscle stiffness and oral pentazocine. Arch Intern Med 1984;144: 1897-1 898 7. Adams EM, Horowitz HW, Sundstrom WA. Fibrous myopathy in association with pentazocine. Arch Intern Med 1983;143:2203-2204
