Neurofibromas can occur in any site, both deep soft tissues and superficial cutaneous lesions. FIGURE 6.1.5 A focus of calcification of calcifying aponeurotic fibroma with a peripheral halo of more rounded epithelioid cells. Unlike the previous variants, this lesion is very closely linked to NF1 and is pathognomonic of the disease. Hyaline fibromatosis is an autosomal recessive disorder that tends to affect children very early in life. Most display small nuclei with comma or hook shapes embedded in a fibrous network. In extra-abdominal locations, fibromatosis occurs in a multitude of sites, including the extremities, trunk, and head and neck regions (Figure 6.3.1). In the diffuse form of neurofibroma, the tumor cells tend to be small and relatively homogeneous. The appearance of this lesion has also been compared to a “bag of worms.”. return false; The name of these often ends in “sarcoma.” The tumor is diverse in appearance and several different cell lines produce tumors of similar appearance. Spindle cells are of mesenchymal origin, and form the body's connective tissue, fat, muscle, bone, cartilage and blood vessels. The fat component may be interspersed throughout or, in more mature lesions, confined to the periphery. The appearance of this lesion has also been compared to a “bag of worms.” As mentioned in the schwannoma section (Section 6.5), “hybrid” types of lesions, with features of both schwannoma and neurofibroma, are not uncommon. Nuchal fibroma is a rare, benign lesion with a strong predilection for the dermis and superficial subcutaneous tissues of the posterior neck or upper back. Signs and symptoms of NF1, as well as severity of disease, are notoriously variable. }); Small vessels can be identified throughout the lesion; these are relatively inconspicuous and normal in shape and caliber. This is a normal variant of neurofibroma and should not be misinterpreted as malignancy. BENIGN AND LOW-GRADE SPINDLE CELL TUMORS window.WPCOM_sharing_counts = {"https:\/\/basicmedicalkey.com\/benign-and-low-grade-spindle-cell-tumors\/":311177}; The most commonly affected sites include upper and lower extremities, hands and feet, upper back, and the abdominal wall (Figure 6.1.15). FIGURE 6.1.15 Imaging of a desmoplastic fibroblastoma located in the superficial soft tissues of the foot. These are usually round- or fusiform-shaped masses that may or may not have an associated peripheral nerve. FIGURE 6.1.6 Nuchal fibroma is a poorly delineated proliferation of dense fibrous tissue. Aspirates are of variable overall cellularity with a predominance of cohesive small tissue fragments (Figure 6.4.6). Grossly, it is often compared to a “bag of worms” because of the irregular growth pattern of numerous nerve small nerve fascicles.
FIGURE 6.1.4 A low-power view of calcifying aponeurotic fibroma showing its fibromatosis-like infiltrating appearance. There may be rare elongated vessels present throughout. Histologically, this lesion is composed of a moderately cellular proliferation of spindled cells arranged in interlacing fascicles. The defining feature of inclusion body fibromatosis is the presence of small intracytoplasmic red inclusions. There may be rare elongated vessels present throughout. FIGURE 6.1.11 Fibroma of tendon sheath is usually sclerotic and relatively paucicellular. FIGURE 6.3.5 Immunohistochemical staining for beta-catenin. Depending on the age of the lesion, different secondary characteristics may be identified. They comprise a mixture of normal fat and hypocellular fibrous tissue (Figure 6.2.2). Most display small nuclei with comma or hook shapes embedded in a fibrous network. FIGURE 6.1.12 Inclusion body fibromatosis showing entrapment of skin adnexal structures. Elastofibromas generally reach a relatively large size (5 to 10 cm) before patients seek medical attention. NLM } Unlike schwannomas, cystic degeneration is not a common feature. var windowOpen; Hyaline fibromatosis is an autosomal recessive disorder that tends to affect children very early in life. FIGURE 6.1.9 The immature element of fibrous hamartoma of infancy tends to be composed of slightly larger cells that often display a whorled or organoid appearance. This may somehow provide a stimulus to formation of the lesion in individuals who may be prone to forming desmoids. 6.5 Schwannoma It is poorly delineated and presents as a slow-growing painless soft tissue mass. Elastofibroma may be partially induced by repetitive traumatic injury. Depending on the age of the lesion, different secondary characteristics may be identified. This example is extensively hyalinized and sclerotic to the point that it almost resembles a keloid. Treatment of fibromatosis is largely surgical.
Because of the dense, fibrous nature of fibromatosis, it often yields unsatisfactory specimens on needle aspiration biopsy. Muscle. It presents as a small, very firm, and usually painless nodule. FIGURE 6.3.4 A more cellular example of fibromatosis. /* ]]> */ The cytoplasm is amphophilic and cell boundaries are indistinct. Growth is slow, insidious, and usually painless. They are centered in the soft tissues, but cause a dome-shaped mass, which produces tightness and redness of the overlying skin. Spindle cell carcinoma, also termed carcinosarcoma, pseudosarcoma, polypoid carcinoma, sarcomatoid carcinoma, and spindle cell variant of squamous cell carcinoma, is a rare type of malignant tumor that often grows as an exophytic polypoid lesion (see also Chapter 20). | A 45-year-old member asked: is a spindle cell tumor almost always malignant? FIGURE 6.3.2 Diffuse or aggressive fibromatosis often entraps fat and individual fibers of adjacent skeletal muscle. Cancer 1981;48:L1615-22. It occurs most commonly on the palmar surfaces of the hands as well as the plantar surfaces of the feet. FIGURE 6.1.17 Desmoplastic fibroblastoma with a hypocellular myxocollagenous background. Previously, most were diagnosed as either smooth muscle or neural tumors. Dermatofibroma expresses Factor XIIIa immunohistochemically, but usually does not show diffuse positivity for CD34. Elastofibromas generally reach a relatively large size (5 to 10 cm) before patients seek medical attention. In addition to multiple colonic adenomas, they also have an increased incidence of fibromas, osteomas, and skin lesions. }); spindle cell tumor benign. // If there's another sharing window open, close it. It is an extremely rare entity, but should be considered in an infant who develops one or more fibrous lesions of the distal digits of the hands or feet. There is a high incidence of local recurrence. The features described in the preceding overlap those of a number of lesions including scar and normal fibrous tissue. 6.3 Fibromatosis Two subtypes of neurofibroma (diffuse and plexiform) are more clearly linked to NF1, but affected patients often have solitary neurofibromas as well. CYTOLOGIC FEATURES The germline mutation is inherited as an autosomal dominant disorder, but de novo mutations are common as well. Myofibroblastic, fibroblastic and myoid lesions of the breast. // If there's another sharing window open, close it. It is a very aggressive form of cancer, and patients who are diagnosed generally do not live more than five years. Histologically, they are comprised of a poorly delineated dermal proliferation of spindled cells (Figure 6.1.1). The other category of cell type is spindle cells tumors. FIGURE 6.1.6 Nuchal fibroma is a poorly delineated proliferation of dense fibrous tissue. Neurofibroma is the one of the major subtypes of benign peripheral nerve sheath tumors (the other being schwannoma). This type of neurofibroma also likes to travel along fascial planes and insinuates itself into subcutaneous fat in the same manner as fibromatosis or dermatofibrosarcoma protuberans (Figure 6.4.4). jQuery(this).next('.code').toggle('fast', function() { 6.9 Angiomyofibroblastoma There is often a cracking artifact between the very dense and coarse bundles of fibrous tissue. Spindle cell lesions of the breast encompass a broad spectrum of entities. This often first manifests as focal nuclear pleomorphism and hyperchromasia within one of the bundles or whorls of a plexiform neurofibroma. FIGURE 6.2.1 This location between the scapula and thoracic wall is classic for elastofibroma. Dermatofibroma expresses Factor XIIIa immunohistochemically, but usually does not show diffuse positivity for CD34. Some refer to this as a “shredded carrots” type of pattern. In addition, there are many different phenotypic abnormalities: café au lait spots, axillary freckles, optic glioma, and Lisch nodules in the iris, in addition to neurofibromas. In extra-abdominal locations, fibromatosis occurs in a multitude of sites, including the extremities, trunk, and head and neck regions (Figure 6.3.1). Although most of these tumors are benign, some rare PEComas are malignant (cancer). Elastofibroma may be partially induced by repetitive traumatic injury. Desmoid tumors form firm mass lesions that may appear circumscribed on gross inspection, but are microscopically infiltrative. FIGURE 6.1.9 The immature element of fibrous hamartoma of infancy tends to be composed of slightly larger cells that often display a whorled or organoid appearance. Neurofibromas demonstrate immunohistochemical staining for S100 protein, but not as diffusely or strongly as in schwannomas. Rare fragments of dense stroma and bland spindle cells may be present. They belong to the family of peripheral neuroblastic tumors (pNTs) which include neuroblastoma, ganglioneuroblastoma, and ganglioneuroma. _stq = window._stq || []; Unlike solitary neurofibromas, these are ill defined and extremely infiltrative. FIGURE 6.2.5 In the perpendicular plane, the elastin fibers appear as pink dots or large globules. Dermatofibromas are common benign lesions of fibrohistiocytic origin that tend to occur in the dermis and subcutaneous soft tissues. Unlike the previous variants, this lesion is very closely linked to NF1 and is pathognomonic of the disease. It has a distinctive predilection for the axillary region, but occasionally can occur in other sites including upper arm and shoulder, thigh, groin, back, and forearm. NF1 is caused by a mutation in the NF1 gene located on chromosome band 17q11.2 that encodes for a tumor suppressor protein known as neurofibromin. Rare stripped nuclei are often identified in the background. Extensive or diffuse infiltration should not be present. In more cellular lesions, mitotic figures may be prominent. Individual cell nuclei are sparse and often very widely spaced. Others are more cellular and are comprised of fascicles of plump myofibroblast-type cells arranged in herringbone and storiform patterns. Mitoses are usually not readily identified in solitary (benign) neurofibroma. They can occasionally recur after excision, but have not been reported to metastasize. return false; Extensive or diffuse infiltration should not be present. Deep fibromatosis, or desmoid tumor, represents a more difficult problem. It presents as a small, very firm, and usually painless nodule. These may be difficult to see on routine hematoxylin and eosin, but are often highlighted by Masson’s trichrome stain or can be highlighted by immunohistochemical staining for SMA (Figure 6.1.13). Because this lesion is infiltrative, it may be difficult to remove completely, and there is a relatively high risk of local recurrence. FIGURE 6.4.6 Aspirates of neurofibroma tend to be relatively hypocellular. When desmoid is suspected or in the differential of a low-grade fibroblastic lesion, immunohistochemical detection of beta-catenin can be useful. The loose component is often arranged in small islands dispersed throughout the lesion (Figure 6.1.9). FIGURE 6.2.6 An elastin stain highlights the abnormal elastic fibers. Tumors composed of benign spindle cells, with variable lines of differentiation. They also have fine, open chromatin and a prominent nucleolus. Lipofibromatosis is a benign pediatric tumor comprising a mixture of mature-appearing fat and a fibromatosis-like spindle cell proliferation. In addition, neurofibromas are often infiltrated by inflammatory cells and histiocytes. It is usually very well circumscribed, and an attachment to a tendon is often noted at the time of excision (Figure 6.1.10). } Fibrous hamartoma of infancy is a lesion that occurs in the first 2 years of life. It displays evidence of myofibroblastic differentiation in that it displays positive immunohistochemical staining for SMA. The superficial fibromatoses are fairly common, affecting an estimated 20% of the population at some point in life. The plexiform variant of neurofibroma should be examined very carefully for evidence of malignant transformation. Calcifying aponeurotic fibroma is a rare tumor with a predilection for children and... NUCHAL FIBROMA. Pathologica. J Clin Pathol. The spindled cells are arranged in short fascicles, usually with a vague storiform configuration (Figure 6.1.3). [CDATA[ */ Alternative therapies, including radiation, tamoxifen, and tyrosine kinase inhibitors can augment the standard surgical approach in patients who experience multiple recurrences. Context.—There are several benign, predominantly spindle cell, mesenchymal proliferations involving the mucosa and/or submucosa in the gut, which present as polyps and pathologists see as polypectomy specimens.These include perineuriomas, Schwann cell nodules, ganglioneuromas, leiomyomas of the muscularis mucosae, inflammatory fibroid polyps, and granular cell tumors. Histologically, nuchal-type fibromas are characterized by a dense, hypocellular collagneous proliferation throughout the superficial soft tissues. They are composed of dense, hypocellular fibrous tissue, occasionally with peripheral entrapment of fat or muscle. There is often focal finger-like extension into the subcutaneous soft tissues. Nuchal-type fibromas are painless and can often reach a large size and tend to be infiltrative. Histologically, fibroma of the tendon sheath is bland and paucicellular (Figure 6.1.11). FIGURE 6.1.2 Deep extent of a dermatofibroma. This lesion tends to occur in the hands and feet of children, with an age range of infancy to adolescence. Unlike solitary neurofibromas, these are ill defined and extremely infiltrative. Spindle cell carcinoma is a type of cancer which usually originates in the connective tissues of the body. Dermatofibromas are common benign lesions of fibrohistiocytic origin that tend to occur in the dermis and subcutaneous soft tissues. Material is usually present as dense cohesive fragments of fibrous tissue with spindled cells attached. What are these tumors? TABLE 6.4.1 Criteria for Neurofibromatoses Types 1 and 2. 6.12 Gastrointestinal Stromal Tumor On regular hematoxylin- and eosin-stained sections, these are easily overlooked and may appear as very subtle pink strands or globules of pink material (Figures 6.2.3 and 6.2.4). FIGURE 6.1.13 Masson’s stain is helpful in highlighting the small intracytoplasmic inclusion bodies that are characteristic of this inclusion body fibromatosis. 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