Hamstring lump in two muscular dystrophies: A novel observation
Dheeraj Rai1, Hardeep S Malhotra1, Ravindra K Garg1, Suman Kushwaha2, Sujata Chaturvedi3, Neeraj Kumar1 1 Department of Neurology, Chhatrapati Shahuji Maharaj Medical University, Lucknow, Uttar Pradesh, India 2 Department of Neurology, Institute of Human Behaviour & Allied Sciences (IHBAS), Dilshad Garden, Delhi, India 3 Department of Neuropathology, Institute of Human Behaviour & Allied Sciences (IHBAS), Dilshad Garden, Delhi, India
Date of Web Publication
Correspondence Address: Hardeep S Malhotra Department of Neurology, Chhatrapati Shahuji Maharaj Medical University, Lucknow, Uttar Pradesh India
Source of Support: None, Conflict of Interest: None
How to cite this article: Rai D, Malhotra HS, Garg RK, Kushwaha S, Chaturvedi S, Kumar N. Hamstring lump in two muscular dystrophies: A novel observation. Neurol India 2012;60:431-2
Muscular dystrophies result from diverse defects in muscle proteins associated with the extracellular matrix, cell membrane, cellular enzymes, organelle or sarcomere function, and nuclear envelope. Duchenne muscular dystrophy (DMD) is caused by mutations in the dystrophin gene located on the X-chromosome (Xp21.1), which encodes for dystrophin protein.  Calpainopathy is an autosomal recessive limb girdle muscular dystrophy (LGMD-2A) caused by mutations in the gene that encodes the proteolytic enzyme calpain-3, mapped at 15q15.1-q21.1.  Selective muscle involvement is well known in muscular dystrophies and various clinical signs based on this have been described. ,,
We describe a patient of DMD with unusual lumps in the hamstrings and soleus, and another patient of LGMD-2A with unusual lumps in the hamstrings and quadriceps [Table 1] and [Figure 1]. Patient with DMD had a unique, not described earlier, hamstrings lump akin to "diamond on quadriceps" as well as markedly prominent soleus jutting out from the two heads of gastrocnemius. Patient with calpainopathy had "diamond on quadriceps" as well as "diamond on hamstrings". Although immunoblot was not available, we feel that the phenotype, histopathological findings and immunopositivity for dystrophin, merosin, α-sarcoglycan, and dysferlin, provided sufficient substrate to make the diagnosis of calpainopathy with fair amount of certainty. The presence of lobulated fibers, in the setting of a normal immunohistochemical pattern, is supportive in this regard to dissect out calpainopathy from the various chronic myopathies in which they may be seen.
Figure 1: Histopathological examination of the biopsied muscle of case 2. Frozen section (a). H and E, ×200, depicts the internalization of the nuclei and splitting of muscle fibers (arrows). NADH staining (b), x400, reveals lobulated fibers (asterisk) while nuclear clumping (arrow) in fibers is evident in the paraffin embedded (H and E, ×400) (c). Immunohistochemistry shows continuous membrane immunopositivity for dysferlin (d)
While the process of differential and selective involvement of muscle groups or fascicles leads to enlargement of some muscles, it may lead to wasting of other muscles or different parts of a single muscle. , The demonstration of this combination of selective atrophy, selective preserved bulk, and the selective enlargement occurring (or becoming more conspicuous) in a state of partial contraction or in a particular posture has been the basis of the various clinical signs described in different muscular dystrophies.  Two such signs observed in the lower limbs, "diamond on quadriceps" sign in dysferlinopathy  and "lumps and bumps' sign on quadriceps in sarcoglycanopathy,  exemplify this selective dystrophic process. Quadriceps and hamstrings are involved in movements around the hip and knee joints and are affected early in the disease course of DMD and LGMDs. These lumps involving the quadriceps and hamstring muscles can be explained by the selective wasting of fascicles within the muscle, with preserved part of the muscle becoming prominent on partial activation. Being long-length muscles, trauma to the fibers secondary to an abnormal stretch also remains a possibility. Equally important is the fact that replacement of the normal muscle with fibro-fatty tissue along the length of the muscles leads to abnormal intermittent tucks and thus better appreciation of localized changes in comparison to other muscles, which is also the reason for similar multiple lumps primarily being described in the quadriceps and biceps, and now in the hamstrings, as in our case. Prominence of soleus in DMD, just as in the case of gastrocnemius, seems to have occurred secondary to relative preservation as well as hypertrophy. Lumps involving quadriceps have classically been described in dysferlinopathy and sarcoglycanopathy but its occurrence in LGMD- 2A has never been highlighted. The presence of lumps in the hamstring in DMD and LGMD-2A has also not been described so far. We additionally wish to highlight prominent soleus in DMD as a separate noticeable phenomenon. We cannot predict how far the extrapolation of these described signs goes, but definitely, they certify the phenotypic heterogeneity, and at least a moderate overlap in them. Analysis of these findings in a larger group will shed more light on their predictive value.
Fanin M, Nardetto L, Nascimbeni AC, Tasca E, Spinazzi M, Padoan R, et al. Correlations between clinical severity, genotype and muscle pathology in limb girdle muscular dystrophy type 2A. J Med Genet 2007;44:609-14. [PUBMED]