The Journal of Dermatology Vol. 18: 161-166,1991
Malignant Granular Cell Tumor Atsumichi Urabe, Shuhei Imayama, Shinichiro Yasumoto, Juichiro Nakayama and Yoshiaki Hori Abstract
A malignant granular cell tumor (MGCT) appeared on the subungual tissue of the right index finger of a 51-year-old woman. Two years after resection of the tumor, it recurred, and the finger finally had to be amputated. Six months later, she noticed multiple cutaneous nodules on her trunk. Despite chemotherapy and X-ray irradiation, the patient died 18 months after the second operation. Histology of the specimen revealed a proliferation of both polygonal and spindleshaped cells with large hyperchromatic nuclei and an eosinophilic granular cytoplasm. Peripheral nerves were encompassed by the tumor cells. Immunohistochemically, the tumor cells were positive for S-100 protein and Leu 7 (myelin-associated glycoprotein). These findings support the hypothesis that MGCT cells are of Schwarm cell origin.
Key words:
granular cell tumor; malignant tumor; Schwarm cell; immunohistochemistry
Introduction Malignant granular cell tumor (MGCT), a rare malignant neoplasm, comprises approximately 1%~2% of all granular cell tumors. Since the first case of this entity was reported by Ravich et al. (1) as malignant granular cell myoblastoma, approximately 30 such cases have been described in the world literature (2-8). Recent immunohistochemical investigations support a Schwarm cell origin for the benign granular cell tumor (8). We report here the enzyme histochemical, immunohistochemical, and ultrastructural findings of MGCT and discuss its nature.
Report of a Case A 51-year-old woman complained of a small reddish nodule present for three years under the nail of her right index finger (Fig. 1). When resected, the tumor was about 0.5 em in diameter and was accompanied by destruction of the nail. Received October 22, 1990; accepted for publication February 12, 1991. Department of Dermatology, Kyushu University, Faculty of Medicine, Fukuoka, Japan. Reprint requests to: Dr. A. Urabe, Department of Dermatology, Kyushu University, Faculty of Medicine, 3-1-1 Maidashi, Higashi-ku, Fukuoka-ciry, Fukuoka 812, Japan.
Fig, 1. A reddish small nodule on the nail bed of the right index finger. Two years later, the tumor recurred and rapidly increased in size. She was admitted to an hospital for surgery. At that time, the growth measured 2.5 em in diameter. It was firm and partly eroded. The finger had''to be amputated. Six months later, she noticed multiple cutaneous nodules on her trunk and was admitted to our hospital for chemotherapy (corticosteroid and cisplatin) and X-ray irradiation. Most of the cutaneous nodules disappeared or were reduced in size. However, the chemotherapy had to be discontinued because of renal dysfunction.
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Fig. 2. Light microscopic features of an incisional biopsy specimen. A: Tumor cells proliferating in the upper dermis (H&E, x82). B: A tumor cell containing numerous eosinophilic granules (H&E, xl,120).
Numerous cutaneous nodules then reappeared on the trunk and extremities, and a chest X-ray revealed multiple nodular shadows in both lungs and the swelling of hilar lymph nodes. She died one year after admission.
Materials and Methods Tissue samples of the cutaneous lesions were obtained from both the primary lesion on the amputated finger and a metastatic lesion on the abdomen. Histologic sections of formalin-fixed, paraffin-embedded tissue were processed for routine light-microscopic examination and stained with either hematoxylin and eosin or Fontana-Masson's technique. Five /lm frozen sections were prepared for the Dopa reaction. A conventional enzyme histochemical technique was used for detection of acid phosphatase. For the immunohistochemical studies, the following antibodies were used: S-100 protein (Milab, 1:100 dilution), Leu 7 (Becton Dickinson, 1:50), vimentin (Labsystems, 1:100),a-actin (Sigma, 1:500), KL-1 (Immunotech, 1:100) and epithelial membrane antigen (EMA) (Dakopatts, 1:200). To detect
the binding sites of S-lOO protein and Leu 7, the ABC immunoperoxidase technique was applied to 5 /lm paraffin sections. For the other antibodies, ABC immunofluorescent staining was done on 5 uiu frozen sections, using biotinylated anti-mouse IgG (1 :40 dilution) and streptavidin-fluorescein isothiocyanate conjugate (1:40). For the ultrastructural study, the tissue specimens were minced into small pieces, fixed in 3% glutaraldehyde buffered with O.IM sodium cacodylate, and post-fixed in buffered 1% osmium tetroxide. Thin sections were stained with uranyl acetate and lead citrate and examined under JEOL 100CX and Hitachi H7000 electron microscopes.
Results Light microscopically, sections obtained at the initial operation showed polygonal cells scattered in the upper dermis with atypical nuclei and eosinophilic granular cytoplasm (Figs. 2A and B). Dilatation of the capillaries and a moderate inflammatory infiltration were present. Necrotic exudate was present on the surface of the lesion.
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Fig. 3. Light microscopic features of the tumor obtained from the amputated finger. A: The tumor was composed of both spindle-shaped and polygonal cells with varying numbers of eosinophilic granules (H&E, x21O). B: Peripheral nerves in the tumor nests (H&E, x112).
B Fig. 4. Immunohistochemistry. Tumor cells showed a positive reaction to both S-IOO protein (A) and Leu 7 (B) (immunoperoxidase staining, x300).
The tumor obtained from the amputated finger consisted of a lobulated mass composed of both spindle-shaped and polygonal cells (Fig. 3A). The cytoplasm of the tumor cells was deeply or coarsely eosinophilic, depending on the number of eosinophilic granules. Giant cells with multiple nuclei and mitotic figures were also present (27/10HPF). Small peripheral nerves were seen in the tumor nests (Fig. 3B). Metastatic cutaneous nodules obtained from the abdomen were composed of anaplastic cells with large hyperchromatic nuclei and eosinophilic cytoplasm. There were numerous mitotic figures. The tumor cells were positive for acid phosphatase to varying degrees. Melanin was not detected with Fontana-Masson's staining, and
the DOPA reaction was negative. Immunohistochemically, the tumor cells were positive for 5-100 protein (Fig. 4A), Leu 7 (Fig. 4B), and vimentin, but negative for (Xactin, KL-1, and EMA. Around the tumor nests, Leu 7 positive natural killer cells were frequently seen. Ultrastructural studies confirmed that the tumor cells, most of which appeared granular under light microscopy, contained numerous granules which were membrane-bound, round to spheroid or even rod shaped, and which ranged from 100 to 1600 nm in diameter (Figs. 5, 6). These granules exhibited a wide spectrum of contents, ranging from a relatively dense homogenous material to a mixture of fragmented membranes, lipid and other cytoplasm-
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Fig. 5. An electron micrograph of the metastatic nodular lesion. Irregular nuclei with inclusions and plump cytoplasm with relatively dense granules were noted (x5,700).
ic debris, including myelinated structures, which presumably represented primary and secondary lysosomes. The tumor cells were also marked by pleomorphic nuclei with irregular and large amounts of heterochromatin and occasional inclusion bodies. Near these nuclei were prominent cytoplasmic organellae: mitochondria, smooth endoplasmic reticulum, Golgi vesicles, and lysosomal granules. The tumor cells exhibited peripheral short processes, but no surrounding basement membranes or intercellularjunctions were evident. Discussion
The results obtained from light, enzyme histochemical, immunohistochemical, and ultrastructural studies were consistent with those of MGCT reported in the literature (3, 4, 6-8). In 1955, Gamboa reviewed 10 cases and obtained evidence for two types of MGCT, a
"histologically and clinically malignant type" and a "histologically benign, but clinically malignant type" (9). In our patient, the initial biopsy specimen showed a proliferation of atypical cells; therefore it probably belonged to the former category of his classification. Since MGCT cells have an eosinophilic granular cytoplasm, one must differentiate this tumor from both alveolar soft part sarcoma (ASPS) and paraganglioma, which have a similar histological appearance of the constituent cells. However, this distinction is not difficult because of the characteristic organoid growth patterns observed in both ASPS (10) and paraganglioma (11). The immunohistochemical findings of these tumors also differ from those of MGCT; ASPS is negative for S-100 protein and myelin proteins (10), and paraganglioma is positive for neurofilament (11). The malignant granular cells varied in their
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Fig. 6. The granules in the tumor cells exhibited the characteristics of primary or secondary lysosomes ranging from small, relatively dense granules to large ones containing membranous debris (x17,OOO).
amounts of eosinophilic granules; constituent cells with an almost clear cytoplasm were occasionally identified. Since these tumor cells do express the antigen for S-100 protein, differentiation from clear cell sarcoma (CCS) may be more problematic. CCS is a tumor of neural crest origin; some investigators have considered it to be a deep and unusual form of malignant melanoma. Therefore, evidence of melanin production is diagnostically important for the differentiation from MGCT. Almost 50% of the cases of CCS react positively to FontanaMasson's staining, and melanosomes in varying stages of development are observed in most cases with electron microscopy (12). Several immunohistochemical analyses of MGCT have been reported (2-8). All cases :xamined had cell populations which were I~munoreactive for S-lOO protein. Leu 7 positIve tumor cells were observed in two cases. In
one case each, the tumor cells were positive for myelin basic protein and for cathepsin-B: one of two immunoreacted with vimentin. Focal cytoplasmic staining for desmin was seen in one of two, but this case showed no reaction to muscle-specific actin. Neurofilament and glial fibrilary acidic protein were not detected in one case each. The presence of carcinoembryonic antigen was noted in one of the three cases examined; however this reactivity may have been due to cross-reacting antibodies against antigens associated with lysosomes (3). Leu 7 (HNK-l) antibody is a marker for both human ~atural killer and Schwarm cells. It has been reported that this antibody reacts with a myelin-associated glycoprotein contained in both pe~pheral and central myelin sheaths (13) and III a variety of neurogenic tumors (14). Ten. of the 13 benign granular cell tumors studied by Smolle et al. (15) and 12 of2l tumors
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described by Mazur et al. (8) positively immunoreacted to this antibody. All this evidence, coupled with the results obtained from MGCT, including our case, suggest that the Leu 7 antibody and 5-100 protein are both useful markers for the diagnosis of MGCT. The immunoreaction of this antibody supports the notion that MGCT is of Schwarm cell origin. References 1) Ravich A, Stout AP, Ravich RA: Malignant granular cell myoblastoma involving the urinary bladder, Ann Surg, 121: 361-372, 1945. 2) Robertson N, McIntosh W, Lamont P, Guthrie W: Malignant granular cell tumour (myoblastoma) of the vulva; report of a case and review of the literature, Histopathology, 5: 69-79,1981. 3) Steffelaar jW, Nap M, v. Haelst UJGM: Malignant granular cell tumor: Report of a case with special reference to carcinoembryonic antigen, Am ] Surg Pathol, 6: 665-672, 1982. 4) Shimamura K, Osamura Y, Ueyama Y, et al: Malignant granular cell tumor of the right sciatic nerve: Report of an autopsy case with electron microscopic, immunohistochemical, and enzyme histochemical studies, Gamer, 53: 524-529, 1984. 5) Khansur T, Balducci L, Tavassoli M: Granular cell tumor: Clinical spectrum of the benign and malignant entity, Gamer, 60: 220-222, 1987. 6) Klima M, Peters j: Malignant granular cell tumor,
ArchPathol Lab Med, 111: 1070-1073,1987. 7) Troncoso P, Ordonez NG, Raymond AK, Mackay B: Malignant granular cell tumor: Immunocytochemical and ultrastructural observations, Ultrastruct Pathol, 12: 137-144, 1988. 8) Mazur MT, ShultzjJ, Myers jL: Granular cell tumor: Immunohistochemical analysis of 21 benign tumors and one malignant tumor, ArchPathol Lab Med, 114: 692-696, 1990. 9) Gamboa LG: Malignant granular-cell myoblastoma, ArchPathol, 60: 663-668, 1955. 10) Enzinger FM, Weiss SW: Alveolar soft part sarcoma, in: Soft Tissue Tumors, 2nd Ed, C. V. Mosby Company, St. Louis, 1988, p 929. 11) Enzinger FM, Weiss SW: Paraganglioma, in: Soft Tissue Tumors, 2nd Ed, C. V. Mosby Company, St. Louis, 1988, p 836. 12) Enzinger FM, Weiss SW: Clear cell sarcoma, in: Soft Tissue Tumors, 2nd Ed, C. V. Mosby Company, St. Louis, 1988, p 945. 13) McGarry RC, Helfand SL, Quarles RH, Roder jC: Recognition of myelin-associated glycoprotein by the monoclonal antibody HNK-l, Nature, 306: 376-378, 1983. 14) Smolle J. Walter GF, Kerl H: Myelin-associated glycoprotein in neurogenic tumours of the skin: An immunohistological study using Leu-7 monoclonal antibody, Arch Dermatol Res, 277: 141-142, 1985. 15) Smolle j, Konrad K, Kerl H: Granular cell tumors contain myelin-associated glycoprotein: An immunohistochemical study using Leu 7 monoclonal antibody, Virchows Arch (Pathol Anat), 406: 1-5,1985.
Malignant Granular Cell Tumor Atsumichi Urabe, Shuhei Imayama, Shinichiro Yasumoto, Juichiro Nakayama and Yoshiaki Hori Abstract
A malignant granular cell tumor (MGCT) appeared on the subungual tissue of the right index finger of a 51-year-old woman. Two years after resection of the tumor, it recurred, and the finger finally had to be amputated. Six months later, she noticed multiple cutaneous nodules on her trunk. Despite chemotherapy and X-ray irradiation, the patient died 18 months after the second operation. Histology of the specimen revealed a proliferation of both polygonal and spindleshaped cells with large hyperchromatic nuclei and an eosinophilic granular cytoplasm. Peripheral nerves were encompassed by the tumor cells. Immunohistochemically, the tumor cells were positive for S-100 protein and Leu 7 (myelin-associated glycoprotein). These findings support the hypothesis that MGCT cells are of Schwarm cell origin.
Key words:
granular cell tumor; malignant tumor; Schwarm cell; immunohistochemistry
Introduction Malignant granular cell tumor (MGCT), a rare malignant neoplasm, comprises approximately 1%~2% of all granular cell tumors. Since the first case of this entity was reported by Ravich et al. (1) as malignant granular cell myoblastoma, approximately 30 such cases have been described in the world literature (2-8). Recent immunohistochemical investigations support a Schwarm cell origin for the benign granular cell tumor (8). We report here the enzyme histochemical, immunohistochemical, and ultrastructural findings of MGCT and discuss its nature.
Report of a Case A 51-year-old woman complained of a small reddish nodule present for three years under the nail of her right index finger (Fig. 1). When resected, the tumor was about 0.5 em in diameter and was accompanied by destruction of the nail. Received October 22, 1990; accepted for publication February 12, 1991. Department of Dermatology, Kyushu University, Faculty of Medicine, Fukuoka, Japan. Reprint requests to: Dr. A. Urabe, Department of Dermatology, Kyushu University, Faculty of Medicine, 3-1-1 Maidashi, Higashi-ku, Fukuoka-ciry, Fukuoka 812, Japan.
Fig, 1. A reddish small nodule on the nail bed of the right index finger. Two years later, the tumor recurred and rapidly increased in size. She was admitted to an hospital for surgery. At that time, the growth measured 2.5 em in diameter. It was firm and partly eroded. The finger had''to be amputated. Six months later, she noticed multiple cutaneous nodules on her trunk and was admitted to our hospital for chemotherapy (corticosteroid and cisplatin) and X-ray irradiation. Most of the cutaneous nodules disappeared or were reduced in size. However, the chemotherapy had to be discontinued because of renal dysfunction.
162
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Fig. 2. Light microscopic features of an incisional biopsy specimen. A: Tumor cells proliferating in the upper dermis (H&E, x82). B: A tumor cell containing numerous eosinophilic granules (H&E, xl,120).
Numerous cutaneous nodules then reappeared on the trunk and extremities, and a chest X-ray revealed multiple nodular shadows in both lungs and the swelling of hilar lymph nodes. She died one year after admission.
Materials and Methods Tissue samples of the cutaneous lesions were obtained from both the primary lesion on the amputated finger and a metastatic lesion on the abdomen. Histologic sections of formalin-fixed, paraffin-embedded tissue were processed for routine light-microscopic examination and stained with either hematoxylin and eosin or Fontana-Masson's technique. Five /lm frozen sections were prepared for the Dopa reaction. A conventional enzyme histochemical technique was used for detection of acid phosphatase. For the immunohistochemical studies, the following antibodies were used: S-100 protein (Milab, 1:100 dilution), Leu 7 (Becton Dickinson, 1:50), vimentin (Labsystems, 1:100),a-actin (Sigma, 1:500), KL-1 (Immunotech, 1:100) and epithelial membrane antigen (EMA) (Dakopatts, 1:200). To detect
the binding sites of S-lOO protein and Leu 7, the ABC immunoperoxidase technique was applied to 5 /lm paraffin sections. For the other antibodies, ABC immunofluorescent staining was done on 5 uiu frozen sections, using biotinylated anti-mouse IgG (1 :40 dilution) and streptavidin-fluorescein isothiocyanate conjugate (1:40). For the ultrastructural study, the tissue specimens were minced into small pieces, fixed in 3% glutaraldehyde buffered with O.IM sodium cacodylate, and post-fixed in buffered 1% osmium tetroxide. Thin sections were stained with uranyl acetate and lead citrate and examined under JEOL 100CX and Hitachi H7000 electron microscopes.
Results Light microscopically, sections obtained at the initial operation showed polygonal cells scattered in the upper dermis with atypical nuclei and eosinophilic granular cytoplasm (Figs. 2A and B). Dilatation of the capillaries and a moderate inflammatory infiltration were present. Necrotic exudate was present on the surface of the lesion.
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Malignant Granular Cell Tumor
Fig. 3. Light microscopic features of the tumor obtained from the amputated finger. A: The tumor was composed of both spindle-shaped and polygonal cells with varying numbers of eosinophilic granules (H&E, x21O). B: Peripheral nerves in the tumor nests (H&E, x112).
B Fig. 4. Immunohistochemistry. Tumor cells showed a positive reaction to both S-IOO protein (A) and Leu 7 (B) (immunoperoxidase staining, x300).
The tumor obtained from the amputated finger consisted of a lobulated mass composed of both spindle-shaped and polygonal cells (Fig. 3A). The cytoplasm of the tumor cells was deeply or coarsely eosinophilic, depending on the number of eosinophilic granules. Giant cells with multiple nuclei and mitotic figures were also present (27/10HPF). Small peripheral nerves were seen in the tumor nests (Fig. 3B). Metastatic cutaneous nodules obtained from the abdomen were composed of anaplastic cells with large hyperchromatic nuclei and eosinophilic cytoplasm. There were numerous mitotic figures. The tumor cells were positive for acid phosphatase to varying degrees. Melanin was not detected with Fontana-Masson's staining, and
the DOPA reaction was negative. Immunohistochemically, the tumor cells were positive for 5-100 protein (Fig. 4A), Leu 7 (Fig. 4B), and vimentin, but negative for (Xactin, KL-1, and EMA. Around the tumor nests, Leu 7 positive natural killer cells were frequently seen. Ultrastructural studies confirmed that the tumor cells, most of which appeared granular under light microscopy, contained numerous granules which were membrane-bound, round to spheroid or even rod shaped, and which ranged from 100 to 1600 nm in diameter (Figs. 5, 6). These granules exhibited a wide spectrum of contents, ranging from a relatively dense homogenous material to a mixture of fragmented membranes, lipid and other cytoplasm-
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164
Fig. 5. An electron micrograph of the metastatic nodular lesion. Irregular nuclei with inclusions and plump cytoplasm with relatively dense granules were noted (x5,700).
ic debris, including myelinated structures, which presumably represented primary and secondary lysosomes. The tumor cells were also marked by pleomorphic nuclei with irregular and large amounts of heterochromatin and occasional inclusion bodies. Near these nuclei were prominent cytoplasmic organellae: mitochondria, smooth endoplasmic reticulum, Golgi vesicles, and lysosomal granules. The tumor cells exhibited peripheral short processes, but no surrounding basement membranes or intercellularjunctions were evident. Discussion
The results obtained from light, enzyme histochemical, immunohistochemical, and ultrastructural studies were consistent with those of MGCT reported in the literature (3, 4, 6-8). In 1955, Gamboa reviewed 10 cases and obtained evidence for two types of MGCT, a
"histologically and clinically malignant type" and a "histologically benign, but clinically malignant type" (9). In our patient, the initial biopsy specimen showed a proliferation of atypical cells; therefore it probably belonged to the former category of his classification. Since MGCT cells have an eosinophilic granular cytoplasm, one must differentiate this tumor from both alveolar soft part sarcoma (ASPS) and paraganglioma, which have a similar histological appearance of the constituent cells. However, this distinction is not difficult because of the characteristic organoid growth patterns observed in both ASPS (10) and paraganglioma (11). The immunohistochemical findings of these tumors also differ from those of MGCT; ASPS is negative for S-100 protein and myelin proteins (10), and paraganglioma is positive for neurofilament (11). The malignant granular cells varied in their
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165
Fig. 6. The granules in the tumor cells exhibited the characteristics of primary or secondary lysosomes ranging from small, relatively dense granules to large ones containing membranous debris (x17,OOO).
amounts of eosinophilic granules; constituent cells with an almost clear cytoplasm were occasionally identified. Since these tumor cells do express the antigen for S-100 protein, differentiation from clear cell sarcoma (CCS) may be more problematic. CCS is a tumor of neural crest origin; some investigators have considered it to be a deep and unusual form of malignant melanoma. Therefore, evidence of melanin production is diagnostically important for the differentiation from MGCT. Almost 50% of the cases of CCS react positively to FontanaMasson's staining, and melanosomes in varying stages of development are observed in most cases with electron microscopy (12). Several immunohistochemical analyses of MGCT have been reported (2-8). All cases :xamined had cell populations which were I~munoreactive for S-lOO protein. Leu 7 positIve tumor cells were observed in two cases. In
one case each, the tumor cells were positive for myelin basic protein and for cathepsin-B: one of two immunoreacted with vimentin. Focal cytoplasmic staining for desmin was seen in one of two, but this case showed no reaction to muscle-specific actin. Neurofilament and glial fibrilary acidic protein were not detected in one case each. The presence of carcinoembryonic antigen was noted in one of the three cases examined; however this reactivity may have been due to cross-reacting antibodies against antigens associated with lysosomes (3). Leu 7 (HNK-l) antibody is a marker for both human ~atural killer and Schwarm cells. It has been reported that this antibody reacts with a myelin-associated glycoprotein contained in both pe~pheral and central myelin sheaths (13) and III a variety of neurogenic tumors (14). Ten. of the 13 benign granular cell tumors studied by Smolle et al. (15) and 12 of2l tumors
Urabe et al
166
described by Mazur et al. (8) positively immunoreacted to this antibody. All this evidence, coupled with the results obtained from MGCT, including our case, suggest that the Leu 7 antibody and 5-100 protein are both useful markers for the diagnosis of MGCT. The immunoreaction of this antibody supports the notion that MGCT is of Schwarm cell origin. References 1) Ravich A, Stout AP, Ravich RA: Malignant granular cell myoblastoma involving the urinary bladder, Ann Surg, 121: 361-372, 1945. 2) Robertson N, McIntosh W, Lamont P, Guthrie W: Malignant granular cell tumour (myoblastoma) of the vulva; report of a case and review of the literature, Histopathology, 5: 69-79,1981. 3) Steffelaar jW, Nap M, v. Haelst UJGM: Malignant granular cell tumor: Report of a case with special reference to carcinoembryonic antigen, Am ] Surg Pathol, 6: 665-672, 1982. 4) Shimamura K, Osamura Y, Ueyama Y, et al: Malignant granular cell tumor of the right sciatic nerve: Report of an autopsy case with electron microscopic, immunohistochemical, and enzyme histochemical studies, Gamer, 53: 524-529, 1984. 5) Khansur T, Balducci L, Tavassoli M: Granular cell tumor: Clinical spectrum of the benign and malignant entity, Gamer, 60: 220-222, 1987. 6) Klima M, Peters j: Malignant granular cell tumor,
ArchPathol Lab Med, 111: 1070-1073,1987. 7) Troncoso P, Ordonez NG, Raymond AK, Mackay B: Malignant granular cell tumor: Immunocytochemical and ultrastructural observations, Ultrastruct Pathol, 12: 137-144, 1988. 8) Mazur MT, ShultzjJ, Myers jL: Granular cell tumor: Immunohistochemical analysis of 21 benign tumors and one malignant tumor, ArchPathol Lab Med, 114: 692-696, 1990. 9) Gamboa LG: Malignant granular-cell myoblastoma, ArchPathol, 60: 663-668, 1955. 10) Enzinger FM, Weiss SW: Alveolar soft part sarcoma, in: Soft Tissue Tumors, 2nd Ed, C. V. Mosby Company, St. Louis, 1988, p 929. 11) Enzinger FM, Weiss SW: Paraganglioma, in: Soft Tissue Tumors, 2nd Ed, C. V. Mosby Company, St. Louis, 1988, p 836. 12) Enzinger FM, Weiss SW: Clear cell sarcoma, in: Soft Tissue Tumors, 2nd Ed, C. V. Mosby Company, St. Louis, 1988, p 945. 13) McGarry RC, Helfand SL, Quarles RH, Roder jC: Recognition of myelin-associated glycoprotein by the monoclonal antibody HNK-l, Nature, 306: 376-378, 1983. 14) Smolle J. Walter GF, Kerl H: Myelin-associated glycoprotein in neurogenic tumours of the skin: An immunohistological study using Leu-7 monoclonal antibody, Arch Dermatol Res, 277: 141-142, 1985. 15) Smolle j, Konrad K, Kerl H: Granular cell tumors contain myelin-associated glycoprotein: An immunohistochemical study using Leu 7 monoclonal antibody, Virchows Arch (Pathol Anat), 406: 1-5,1985.
