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PubMed1983

Multiple-bag-fiber muscle spindles in tenuissimus muscles of the cat.

Over 300 complete and incomplete cat muscle spindles were examined in serial transverse sections of tenuissimus muscles in search of spindles with more than two nuclear bag intrafusal muscle fibers. Several histochemical and histological stains were used to identify the intrafusal fibers and assess their motor and sensory innervation. About 13% of the spindles contained either three or four bag fibers rather than the usual two. Every multiple-bag-fiber spindle possessed at least one nuclear bag1 and one nuclear bag2 fiber. The supernumerary bag fibers were either another bag1 and/or bag2 fiber, or a mixed bag fiber. The extra bag fibers had the usual morphologic and histochemical properties of cat nuclear bag fibers. All multiple-bag spindles received primary sensory innervation, and most had secondary sensory endings in addition. Their motor pattern was similar in the number, appearance and disposition of intrafusal motor endings to that of the usual two-bag-fiber spindles. Bag fibers of the same kind shared motor nerve supply in three multiple-bag spindles in which tracings of individual motor axons were obtained histologically. It is unclear whether any functional advantage is conveyed to a muscle spindle by its having more than one bag1 and one bag2 fiber.

Adenosine Triphosphatases↗

PubMed2006

The significance of sigma neurofeedback training on sleep spindles and aspects of declarative memory.

The functional significance of sleep spindles for overnight memory consolidation and general learning aptitude as well as the effect of four 10-minute sessions of spindle frequency (11.6-16 Hz, sigma) neurofeedback-training on subsequent sleep spindle activity and overnight performance change was investigated. Before sleep, subjects were trained on a paired-associate word list task after having received either neurofeedback training (NFT) or pseudofeedback training (PFT). Although NFT had no significant impact on subsequent spindle activity and behavioral outcomes, there was a trend for enhanced sigma band-power during NREM (stage 2 to 4) sleep after NFT as compared to PFT. Furthermore, a significant positive correlation between spindle activity during slow wave sleep (in the first night half) and overall memory performance was revealed. The results support the view that the considerable inter-individual variance in sleep spindle activity can at least be partly explained by differences in the ability to acquire new declarative information. We conclude that the short NFT before sleep was not sufficient to efficiently enhance phasic spindle activity and/or to influence memory processing. NFT was, however, successful in increasing sigma power, presumably because sigma NFT effects become more easily evident in actually trained frequency bands than in associated phasic spindle activity.

Adolescent↗

PubMed1975

Evolution of sleep spindles in childhood.

Twenty-six normal children (age range range 4-68 months) were studied during Stage 2 sleep which occurred within 20 min preceding or following the first three REM periods of the night. Sleep spindles were measured in Fp1T3. The number, length, and percent of sleep spindle activity were found to be maximal at 46 months of age. Beyond 6 months spindle activity decreased to reach minimal values by 27 months, remained fairly constant to 54 months, then rose again to higher values in the oldest subjects. The mean spindle-wave frequency was 1314 c/sec in subjects younger than 40 months, but was 12-13 c/sec in older subjects. Spindle onsets in Fp1T3 and Fp2T4 were more often concurrent in older as compared to younger subjects. Auditory stimulation (binaural clicks, 60 dB above hearing threshold) affected neither the incidence nor the length of spindles during sleep. Because sizable changes in sleep spindle activity are found between 3 months and 5 years of age, and because such changes are relatively consistent between subjects, it is concluded that sleep spindles recorded between frontal and temporal areas may serve as a useful index of neural maturation in the human subject.

Acoustic Stimulation↗

PubMed1996

Frontal cortex leads other brain structures in generalised spike-and-wave spindles and seizure spikes induced by picrotoxin.

Generaliszed spike-and-wave (SW) spindles (5-7 Hz) associated with myoclonic jerks precede the occurrence of regular spikes (2-3 Hz) associated with convulsive seizure induced by picrotoxin. SW spindles occur spontaneously in rodent and cat under some experimental conditions and are considered to be models of human generalised epilepsy. These spindles have been proposed as being led by a thalamic pacemaker. To examine this possibility in picrotoxin-induced SW spindles and seizure spikes, we recorded EEG using chronically implant unipolar electrodes during intravenous picrotoxin infusion in freely behaving rat. The 6 EEG signals were digitally sampled at 1000 Hz. Linear correlation, spectral, coherence and phase analyses were undertaken to determine time differences (TDs) between EEG channels and the brain structure leading seizure activity. One frontal cortex led all other structures during SW spindles. TD between SW spindles in the leading frontal cortex (Fr1) and the contralateral Fr1 was 3.6 + / - 0.5 msec. All ipsilateral structures (hippocampus, thalamus, amygdala, caudate nucleus and occipital cortex) were delayed by more than 3 msec from Fr1 (intralaminar thalamic nuclei - by 6.3 + / - 0.9 msec). TDs of SW spindles between subcortical regions were less than 1.5 msec. Similar relationships with slightly smaller TDs were found with spikes during convulsive seizure except TDs between frontal cortices did not significantly differ from zero. We suggest that seizure activity induced by picrotoxin is led by one Fr1 during SW spindles and by both frontal cortices working as one system during convulsive seizure.

Animals↗

PubMed1995

Modulation of rat neocortical high-voltage spindle activity by 5-HT1/5-HT2 receptor subtype specific drugs.

To investigate the role of serotonin (5-hydroxytryptamine; 5-HT) receptors in the modulation of rat thalamocortical oscillations, we studied the effects of 5-HT1/5-HT2 receptor subtype specific drugs on neocortical high-voltage spindle activity in adult male rats. A 5-HT1A receptor agonist, 8-hydroxy-2-(di-n-propylamino)tetralin (8-OH-DPAT) (0.03, 0.1, 0.3 and 1.0 mg/kg s.c.), had no effect on neocortical high-voltage spindle activity. Furthermore, a mixed 5-HT1/5-HT2 receptor antagonist, methysergide (1.0, 5.0 and 15.0 mg/kg i.p.), had no effect, whereas a non-specific mixed 5-HT1/5-HT2 receptor antagonist, methiothepin (0.2, 1.0 and 5.0 mg/kg i.p.), significantly increased neocortical high-voltage spindles. Of the 5-HT2 receptor antagonists, ritanserin (0.1, 1.0 and 5.0 mg/kg s.c.) had no effect, whereas ketanserin (1.0, 5.0 and 20.0 mg/kg s.c.) increased neocortical high-voltage spindles, but only at the highest dose used. A 5-HT2 receptor agonist, 1-(2,5-dimethoxy-4-iodophenyl)-2-aminopropane (DOI) (0.5, 1.0 and 2.0 mg/kg s.c.), at the two highest doses significantly decreased neocortical high-voltage spindle activity, and this effect was blocked by the 5-HT2 receptor antagonists, ketanserin (1.0, 5.0 and 20.0 mg/kg s.c.) and ritanserin (1.0 and 5.0 mg/kg s.c.), as well as by methiothepin (0.2, 1.0 and 5.0 mg/kg i.p.) and methysergide (1.0, 5.0 and 15.0 mg/kg i.p.). Furthermore, unilateral intrathalamic infusions, but not intrahippocampal control infusions, of DOI (10 and 50 micrograms/1.0 microliters/rat) decreased neocortical high-voltage spindle activity and systemic administration of ketanserin (20.0 mg/kg s.c.) completely blocked this effect. The present results suggest that (1) the serotonergic system modulates rat thalamocortical oscillations as measured by neocortical high-voltage spindle activity, (2) activation of 5-HT2 receptors, possibly located in the thalamus, with a specific 5-HT2 receptor agonist, DOI, causes a reduction in rat neocortical high-voltage spindle activity.

8-Hydroxy-2-(di-n-propylamino)tetralin↗

PubMed1996

Suppression of neocortical high-voltage spindles by nicotinic acetylcholine and 5-HT2 receptor stimulation.

To investigate the roles of the nicotinic acetylcholine receptor and the serotonin (5-hydroxytryptamine; 5-HT) subtype 2 receptor in the modulation of rat thalamocortical oscillations, the effects of systemic (s.c.) administration of nicotine, a nicotinic acetylcholine receptor agonist, and 1-(2,5-dimethoxy-4-iodophenyl)-2-aminopropane (DOI), a 5-HT2 receptor agonist, on neocortical high-voltage spindle activity occurring during quiet waking-immobility behavior in aged (28 months of age) and adult (7 months of age) rats were studied. Nicotine 0.1 and 0.3 mg/kg alleviated the age-related increase of neocortical high-voltage spindles, whereas in adult rats only nicotine 0.3 mg/kg was effective. DOI 0.3, 1.0 and 2.0 mg/kg suppressed high-voltage spindles in both aged and adult rats. In aged rats, a combination of subthreshold doses of nicotine (0.03 mg/kg) and DOI (0.1 mg/kg) decreased neocortical high-voltage spindles, whereas in adult rats two different subthreshold dose combinations (nicotine 0.03 or 0.1 mg/kg+DOI 0.1 mg/kg) had no effect. p-Chlorophenylalanine (400 mg/kg/day i.p. for 3 consecutive days) treatment decreased brain serotonin concentration (> 80% reduction), but did not affect high-voltage spindles. However, in both aged and adult rats, p-chlorophenylalanine treatment blocked the decrease in high-voltage spindle activity produced by DOI 0.3 mg/kg, though not the decrease produced by higher doses of DOI (1.0 and 2.0 mg/kg). It is important that, in adult rats, p-chlorophenylalanine treatment was able to abolish the decrease in high-voltage spindle activity seen after a relatively high dose of nicotine (0.3 mg/kg). The results suggest that nicotinic acetylcholine and 5-HT2 receptors may act in concert to suppress neocortical high-voltage spindling in rats, and that intact brain serotonergic systems may be important for some of the therapeutic effects of nicotine.

Age Factors↗

PubMed1992

Formation of muscle spindles in the absence of motor innervation.

Whether muscle spindles can form in muscles innervated only by afferents was investigated by removing the lumbosacral segment of the spinal cord immediately after crushing the nerve to the medial gastrocnemius (MG) muscle in newborn rats, and administering nerve growth factor for 10 days afterwards. The nerve-crushed MG muscles reinnervated by afferents in the absence of motor innervation were examined at postnatal (P) days 7, 9 and 30 for the presence of spindles by light and electron microscope. Reinnervated MG muscles contained spindle-like encapsulations of 1-4 fibers at 7, 9 and 30 days after the nerve crush. The number of spindles exceeded that of normal MG muscles, suggestive of de novo formation of spindles. All nerve-muscle contacts in the spindles had features of sensory endings, and intrafusal fibers expressed the spindle-specific slow-tonic myosin heavy chain (MHC) isoform at P30. No motor endplates were visible on any muscle fibers and extrafusal fibers were atrophied, as would be predicted in the absence of motor innervation. Thus, efferents are not essential for the formation and differentiation of muscle spindles in reinnervated muscles of neonatal rats.

Animals↗

PubMed1992

Intracellular evidence for incompatibility between spindle and delta oscillations in thalamocortical neurons of cat.

Recent studies have revealed that the thalamus does not only generate spindle oscillations (7-14 Hz), but that it also participates in the genesis of a slower (less than 4 Hz) rhythm within the frequency range of delta waves on the electroencephalogram. In thalamic cells, delta is an intrinsic oscillation consisting of low-threshold spikes alternating with afterhyperpolarizing potentials. It is known from electroencephalographic recordings in humans and animals that slow or delta waves prevail during late sleep stages, whereas spindle oscillations are characteristic for the early stages of sleep. We studied the dependence of spindles and delta oscillations on membrane potential, as well as the effects of spindles on delta oscillations, in thalamocortical neurons of cats under urethane anesthesia and in cerveau isolé preparations (low collicular transections). Spindles appeared at membrane potentials between -55 and -65 mV, whereas delta oscillations occurred by bringing the membrane potential between -68 and -90 mV. Spindles either evoked by cortical stimulation or occurring spontaneously in cerveau isolé preparations prevented delta oscillations. This effect was probably due to the increase in membrane conductance associated with spindles. Barbiturates also blocked delta activity in thalamocortical neurons, probably through the same mechanism. A certain degree of incompatibility between spindles and delta rhythms in thalamocortical cells may explain the prevalence of these two types of oscillations during different stages of sleep with synchronization of the electroencephalogram.

Animals↗

PubMed2005

Presence of 14Hz spindle oscillations in the human EEG during deep anesthesia.

OBJECTIVE: To report on presence of human EEG spindle oscillations on the cortical level within flat periods of the burst-suppression pattern during propofol-induced anesthesia; to search for corresponding oscillations and possible functional connections. METHODS: Artefact-free epochs of spindle activation were selected from the electroencephalograms of opiate-dependent patients undergoing rapid opiate detoxification. Power spectral analysis and source localization using low-resolution-brain-electromagnetic-tomography (LORETA(Key)) were performed. RESULTS: Sinusoidal rhythms with waxing and waning amplitudes appeared after propofol-induced narcosis but no direct correlations could be determined between individual dosage and characteristic spindle attributes. The power maximum stood midline over the cortical areas, especially around C(z). We calculated a peak frequency of 14(+/-1.2) Hz. Motor fields, particularly in the frontal, parietal, and various cingulate areas, were found to be the primary sources of spindle oscillations in the cortex. CONCLUSIONS: The frequent occurrence of these localized spindle sources demonstrates the preference for motor fields. Spindle oscillations observed during propofol-induced narcosis were similar in frequency and shape to those observed in natural sleep. SIGNIFICANCE: The results lend support to models that postulate a close link between the motor system and the organization of behavior. In addition, spindle rhythms under propofol bore some resemblance to spindle types which occur during sleep.

Adult↗

PubMed1996

The effects of cholinergic drugs on rat neocortical high-voltage spindles in ketanserin-treated rats.

To investigate the roles of the cholinergic system and 5-HT2 receptors in the modulation of thalamocortical oscillations, we studied the effects of systemic (s.c.) administration of anticholinesterases (physostigmine, tetrahydroaminoacridine) and muscarinic acetylcholine receptor agonists (pilocarpine, oxotremorine) on spontaneous thalamically generated rhythmic neocortical high-voltage spindles in adult rats pretreated with either saline or ketanserin, a 5-HT2 receptor antagonist. Ketanserin at 20.0 mg/kg increased the number of high-voltage spindles. In saline-treated rats, tetrahydroaminoacridine 3.0 and 9.0 mg/kg was able to decrease high-voltage spindles, whereas in ketanserin 20.0 mg/kg-treated rats only the highest dose of tetrahydroaminoacridine (9.0 mg/kg) decreased high-voltage spindles. Both doses of physostigmine, 0.12 and 0.36 mg/kg, decreased high-voltage spindles in both saline and ketanserin 20.0 mg/kg-treated rats. Lower doses of tetrahydroaminoacridine (1.0 mg/kg) and physostigmine (0.06 mg/kg) were ineffective in both saline- and ketanserin 20.0 mg/kg-treated rats. Pilocarpine 3.0 mg/kg and oxotremorine 0.1 and 0.9 mg/kg decreased high-voltage spindles in saline-treated rats. However, in rats treated with ketanserin 20.0 mg/kg, only the lower doses of pilocarpine (0.3 and 1.0 mg/kg) and oxotremorine (0.03 mg/kg) were able to decrease the high-voltage spindles. The results suggest that activation of the cholinergic system and activation of 5-HT2 receptors have additive effects in the suppression of thalamocortical oscillations and related neocortical high-voltage spindles in rats, thus maintaining effective information processing in thalamocortical networks.

Animals↗

PubMed1999

The first polar body does not predict accurately the location of the metaphase II meiotic spindle in mammalian oocytes.

OBJECTIVE: To evaluate how well polar body location predicts spindle localization and to examine spindle morphology. DESIGN: Randomized, controlled animal study. SETTING: University-affiliated research laboratory. ANIMAL(S): Mature, female golden hamsters. INTERVENTION(S): After superovulation with pregnant mare serum gonadotropin and hCG, metaphase II oocytes were obtained and imaged under digital polarization microscopy. MAIN OUTCOME MEASURE(S): Identify the meiotic spindle in living, unfixed hamster oocytes and determine spindle location relative to the polar body. RESULT(S): Spindles were imaged in 30 oocytes and only in 5 of them could the polar body predict the spindle localization. In the remaining oocytes, the spindles presented a random distribution within the cytoplasm. CONCLUSION(S): These data show that the polar body location is not an accurate predictor for meiotic spindle location in mammalian oocytes.

Animals↗

PubMed1997

Phenotype and proliferation characteristics of cultured spindle-shaped cells obtained from normal human skin and lesions of dermatofibroma, Kaposi's sarcoma, and dermatofibrosarcoma protuberans: a comparison with fibroblast and endothelial cells of the dermis.

Normal human dermis contains mesenchymal cells that are generally referred to as fibroblasts. However the relationships between fibroblasts and endothelial cells with respect to the types of spindle-shaped cells that are present in cultures obtained from tumor bearing-skin is unclear. To explore the potential heterogeneity amongst dermal-derived cells that grow in culture with a spindle-shaped morphology, we compared the immunophenotype and growth characteristics of several types of cells. Besides dermal fibroblasts and microvascular endothelial cells derived from normal adult skin, we also studied large vessel-derived endothelial cells, and spindle-shaped cells derived from three different tumor-bearing dermal-based neoplasms. Kaposi's sarcoma (KS), dermatofibroma (DF), and dermatofibrosarcoma protuberans (DFSP). A broad panel of eight different antibodies were used to immunophenotype the multi-passaged cultured cells. Spindle-shaped cells from all three neoplasms could be distinguished from the normal skin derived fibroblasts by their constitutive expression of factor XIIIa, and the gamma-interferon induced expression of VCAM-1. All seven types of cultured cells stained positive for s-actin and proline-4-hydroxylase, and none of the cells expressed CD34. Both large and small-vessel derived endothelial cells expressed factor VIII, ELAM-1, and VCAM-1. Using two different types of growth media, significant differences were also observed amongst these cultured cell types. Spindle-shaped cells from DFSP did not grow in DMEM containing 10% fetal bovine serum (DMEM-FBS); but they proliferated in KS cell growth medium (KSGM). Spindle-shaped cells from DF grew best in KSGM, but not in DMEM-FBS. KS tumor cells grew well in KSGM, but not in DMEM-FBS. Fibroblasts proliferated in DMEM-FBS, but failed to grow in KSGM; and even when pre-treated with conditioned medium from a transformed KS cell line (i.e. SLK cells), no fibroblast proliferation could be induced in KSGM. These results indicate that KS cell line (i.e. SLK cells), no fibroblast proliferation could be induced in KSGM. These results indicate that even though dermal-derived cells can have an identical spindle-shape by light microscopy, significant heterogeneity can be defined amongst such cells from normal and tumor-bearing human skin. Having established culture conditions to propagate these different cell types and phenotypic criteria to distinguish them from one another, will provide new research opportunities to explore the function and ontogeny of the diverse mesenchymal cells that take on a spindle-shaped morphology in culture.

Adult↗

PubMed2003

Spindle frequency remains slow in sleep apnea patients throughout the night.

BACKGROUND: Our previous data suggested that in normal sleep the frequency of individual sleep spindles would be related to sleep depth and possibly to sleep pressure. Thus far spindle frequency patterns in patients with sleep disorders have not been studied. It would be expected that the spindle frequencies might be affected by sleep fragmentation disturbing the sleep process. METHODS: Twelve apnea patients with age- and sex-matched control subjects were studied with whole-night sleep recordings. Sleep spindles were visually selected and their frequency was determined by spectral analysis. RESULTS: Sleep spindles of the patients were in general slower than in the control subjects. As in our previous study, the frequency of the spindles in the middle-part of the non-rapid eye movement (NREM) sleep episodes increased towards the end of the night in the control group, whereas in the patient group no such increase was found. CONCLUSIONS: The slow spindle frequencies in apnea patients could indicate disturbed sleep and altered neural mechanisms in the structures regulating sleep spindle activity.

Adult↗

PubMed2003

Spindle frequency remains slow in sleep apnea patients throughout the night.

Adult↗

PubMed2000

Autoassociative MLP in sleep spindle detection.

Spindles are one of the most important short-lasting waveforms in sleep EEG. They are the hallmarks of the so-called Stage 2 sleep. Visual spindle scoring is a tedious workload, since there are often a thousand spindles in one all-night recording of some 8 hr. Automated methods for spindle detection typically use some form of fixed spindle amplitude threshold, which is poor with respect to inter-subject variability. In this work a spindle detection system allowing spindle detection without an amplitude threshold was developed. This system can be used for automatic decision making of whether or not a sleep spindle is present in the EEG at a certain point of time. An Autoassociative Multilayer Perceptron (A-MLP) network was employed for the decision making. A novel training procedure was developed to remove inconsistencies from the training data, which was found to improve the system performance significantly.

Adult↗

PubMed2003

Monophasic sarcomatoid carcinoma of the scalp: a case mimicking inflammatory myofibroblastic tumor and a review of cutaneous spindle cell tumors with myofibroblastic differentiation.

BACKGROUND: The evaluation of malignant cutaneous spindle cell tumors is challenged by a diagnostic differential that comprises neoplasms of diverse histogenesis, and a broad immunohistochemical panel may confound the diagnosis when the results suggest multiple lines of differentiation, such as with a combined myofibroblastic and epithelial phenotype. METHODS: We report the case of a solitary scalp nodule that quickly became locally metastatic. A comprehensive panel of immunohistochemistry markers and electron microscopy was evaluated to determine the differentiation of the spindle cells. RESULTS: The tumor, consisting of wavy and slender spindle cells with predominantly bland nuclei, showed immunoreactivity to vimentin, smooth muscle actin, and muscle-specific actin. AE1/AE3, CK5/6, and MNF-116 antibodies were weakly positive in rare cells. However, 34betaE12 showed diffuse positivity in the spindle cell population, thus supporting the diagnosis of a sarcomatoid carcinoma with myofibroblastic differentiation. CONCLUSIONS: The use of 34betaE12 is essential for the evaluation of myofibroblastic spindle cell tumors with rare cytokeratin reactivity. However, even with immunohistochemical and electron microscopic studies, the diagnosis of spindle cell tumors can be confounded by the multiplicity of nosologic equivalents, such as carcinosarcoma, spindle cell carcinoma, and metaplastic carcinoma. The nomenclature of these spindle cell tumors is discussed.

Actin Cytoskeleton↗

PubMed2006

A spindle cell variant of diffuse large B-cell lymphoma possesses genotypic and phenotypic markers characteristic of a germinal center B-cell origin.

Lymphoma with prominent spindle cell features, the so-called spindle cell lymphoma, is an unusual morphological variant of diffuse large B-cell lymphoma. Five new cases of spindle cell lymphoma have been analyzed by a multiparameter approach in order to clarify its clinical and biological features. All patients presented advanced stage disease with extranodal involvement. Vagina was the most common extranodal site. All patients received chemotherapy and are alive in complete remission. Morphologically, all five cases exhibited proliferation of spindle cells with a vaguely storiform pattern highly suggestive of spindle cell neoplasms of nonlymphoid origin. In contrast, the results of immunohistochemical analysis indicated that all five cases were hematolymphoid neoplasms of the B-cell lineage. These lymphomas consisted of a B-cell clonal population which exhibited somatic immunoglobulin and BCL-6 mutations as well as BCL-6 protein expression. The neoplastic spindle cells therefore closely resemble B cells residing in the germinal center. The absence of MUM1 expression in neoplastic spindle cells suggested that neoplastic spindle cells may be related to the early phases of intragerminal center maturation of B cells. The germinal center phenotype, with restricted expression of BCL-6, was associated with the presence of a primary extranodal origin, normal lactate dehydrogenase levels, and good response to treatment.

Adult↗

PubMed2001

Histological and immunohistochemical characterization of extranodal diffuse large-cell lymphomas with prominent spindle cell features.

AIMS: To describe five cases of diffuse large-cell lymphoma with prominent spindle cell components involving skin, nasal-ocular mucosa, and soft tissue. Because of the spindle cell morphology, such cases must be differentiated from true sarcomas arising in or metastasizing to soft tissue, skin, bone, lymph node, or other organs and sites. METHODS AND RESULTS: Formalin-fixed paraffin-embedded archival tissue from five consultation cases of diffuse large-cell lymphoma with prominent spindle cell features involving the skin, nasal-ocular mucosa, and soft tissue in three male and two female patients was studied by histology and immunohistochemistry. Clinicopathological findings were also reviewed for all the patients. By morphology, initial evaluation of the cases suggested spindle cell sarcoma in two cases, inflammatory pseudotumour in one case, large-cell lymphoma in another case, and one case was considered suspicious for malignant lymphoma. Immunohistochemistry demonstrated a B-cell lineage in four of the spindle cell lesions, with a diagnosis of primary cutaneous CD30+ anaplastic large cell lymphoma made for the fifth case. Four of five cases also showed actin reactivity. CONCLUSIONS: Although extremely rare, lymphomas with prominent spindle cell morphology can be encountered in daily surgical pathology practice, and should be included in the differential diagnosis of spindle cell lesions in skin and soft tissue. The observed actin reactivity in four of the five spindle cell lymphomas may lead to a misdiagnosis of leiomyosarcoma if lymphoid markers are not included in the immunohistochemical panel.

Adult↗