Malignant Transformation of Mastocytoma Developed on Skin Mastocytosis Into Cutaneous Mast Cell Sarcoma

Mastocytosis

Mastocytosis is a spectrum of clonal myeloid disorders defined by abnormal growth and accumulation of mast cells in various organ systems. The disease is divided into cutaneous mastocytosis, systemic mastocytosis (SM) and mast cell sarcoma. SM is further categorized into several non-advanced and advanced forms. The prognosis of cutaneous mastocytosis and non-advanced SM is mostly favourable, whereas prognosis and survival in advanced SM and mast cell sarcoma are poor. During the past 15 years, major advances have been made in the diagnosis, prognosis and management of patients with mast cell neoplasms. Management of mastocytosis consists of symptomatic therapy, including anti-mast cell mediator drugs, and cytoreductive agents for patients with advanced disease and selected individuals with non-advanced disease, as well as recognition and prevention of comorbidities such as osteoporosis and anaphylaxis. The preclinical and clinical development of KIT-D816V-targeting drugs, such as midostaurin or avapritinib, mark a milestone in improving management, the quality of life and survival in patients with SM. These agents induce major responses or even remission in people with advanced SM and lead to rapid improvement of mediator-related symptoms and quality of life in symptomatic patients.

Mast cell sarcoma with KIT p.D816V mutation and concurrent systemic mastocytosis

Mast cell sarcoma (MCS) is an extremely rare and aggressive form of mastocytosis characterized by highly atypical mast cells with local invasion, metastatic potential, and poor prognosis. MCS is predominantly a de novo process without recurrent molecular findings or predisposing lesions including various myeloid neoplasms. However, there have been rare case reports of MCS with preceding or concurrent systemic mastocytosis (SM) or cutaneous mastocytosis (CM), which is suggestive of an uncommon progression from SM/CM to MCS. We hereby report a case of MCS in an 84-year-old male with a KIT p.D816V mutation and concurrent SM. KIT p.D816V point mutation is well known as the canonical variant in SM. In our case, MCS with KIT p.D816V mutation is a unique finding in the setting of concurrent SM, highlighting the potential relatedness of these two entities and the progression from SM to MCS, a currently poorly understood phenomenon.

Mast cell sarcoma: clinicopathologic and molecular analysis of 10 new cases and review of literature

Mast cell sarcoma (MCS) is an exceedingly rare form of mastocytosis characterized by invasive malignant mast cell growth and metastatic potential. Diagnosis of MCS is very challenging due to its marked morphologic variations and significant immunophenotypic overlap with other neoplasms. In this study, we undertook an extensive study of 10 cases of MCS from our series, with review of additional 24 cases from the literature, to better clarify the clinicopathologic and molecular features of MCS. From the analyses of our 10 cases, MCS equally involved males and females with a median age of 54.5 years (range 1-63). The bone was the most common site of involvement, as noted in 9/10 of cases. Two patients had prior germ cell tumors (mediastinal germ cell tumor and ovarian dysgerminoma), and concurrent systemic mastocytosis was noted in one of nine patients. Serum tryptase levels were elevated in 6/7 of patients, and 3/9 of patients had mast cell activation symptoms. Morphologically, the tumor cells were typically large and pleomorphic with frequent reactive eosinophils. By immunohistochemical staining, MCS consistently expressed CD43 (8/8), CD117 (10/10), and mast cell tryptase (10/10), as well as CD13 (3/3) and CD33 (10/10), with variable positivity of CD2 (1/9), CD25 (4/9), CD30 (5/8), and CD68 (5/9). Notably, KIT D816V was not detected in nine cases in our study, although two cases had other mutations of KIT gene. Seven out of eight patients received chemotherapy with or without radiotherapy. However, the response was poor, and four out of eight patients died within a median follow-up interval of five months. Taken together, there are no standardized therapeutic regimens available for MCS at this time, and the prognosis is dismal. Therefore, it is critical to further investigate and characterize this rare entity, with the hope of improving diagnostic accuracy and providing more effective, targeted therapies.

Management of a Lumbar Burst Fracture Occurring After a Sneeze in a Patient Affected by Systemic Mastocytosis: A Case Report

CASE

We present a 36-year-old man with L1 burst fracture after a sneeze. He was in follow-up for indolent systemic mastocytosis (ISM), and osteoporosis was treated with bisphosphonate. Owing to neurologic impairment, posterior decompressive laminectomy and thoraco-lumbar fusion with cemented screws were performed.

CONCLUSION

Vertebral fractures in young patients affected by ISM required a multidisciplinary approach and a careful preoperative planning to achieve acceptable results. These fractures are so rare that even an experienced spine surgeon may not come across them during his whole career. Nevertheless, diagnostic tool improvement makes its diagnosis more frequent, that is why every spine surgeon should know this disease.

Case report of a clinically indolent but morphologically high-grade cutaneous mast cell tumor in an adult: Atypical cutaneous mastocytoma or mast cell sarcoma?

We present a case of an adult male with a solitary mast cell tumor of the skin with unusual nuclear pleomorphism and mitotic activity. The tumor was excised, recurred within 2 years, was reexcised after 4 years and did not recur >6 years after diagnosis. The tumor showed progressive cytonuclear atypia and a high mitotic and proliferation rate by Ki67-staining from the onset. No KIT mutations were identified in the tumor and bone marrow. Serum tryptase levels and a bone marrow aspirate and trephine biopsy were normal. Although the histomorphology of the skin tumor was consistent with mast cell sarcoma, the clinical behavior without systemic progression argued against this diagnosis. The tumor was finally considered as atypical mastocytoma, borderline to mast cell sarcoma. Currently, the patient is in close follow-up and still in complete remission.

Childhood Solitary Cutaneous Mastocytoma: Clinical Manifestations, Diagnosis, Evaluation, and Management

BACKGROUND

The diagnosis of solitary cutaneous mastocytoma is mainly clinical, based on lesion morphology, the presence of a positive Darier sign, and the absence of systemic involvement. Knowledge of this condition is important so that an accurate diagnosis can be made.

OBJECTIVE

To familiarize physicians with the clinical manifestations, diagnosis, evaluation, and management of a solitary cutaneous mastocytoma.

METHODS

A PubMed search was completed in Clinical Queries using the key term "solitary cutaneous mastocytoma". The search strategy included meta-analyses, randomized controlled trials, clinical trials, observational studies, and reviews. Only papers published in English language were included. The information retrieved from the above search was used in the compilation of the present article.

RESULTS

Typically, a solitary cutaneous mastocytoma presents as an indurated, erythematous, yellow- brown or reddish-brown macule, papule, plaque or nodule, usually measuring up to 5 cm in diameter. The lesion often has a peau d'orange appearance and a leathery or rubbery consistency. A solitary cutaneous mastocytoma may urticate spontaneously or when stroked or rubbed (Darier sign). Organomegaly and lymphadenopathy are characteristically absent. The majority of patients with skin lesions that erupt within the first two years of life have spontaneous resolution of the lesions before puberty. Treatment is mainly symptomatic. Reassurance and avoidance of triggering factors suffice in most cases.

CONCLUSION

The diagnosis is mainly clinical, based on the morphology of the lesion, the presence of a positive Darier sign, and the absence of systemic involvement. A skin biopsy is usually not necessary unless the diagnosis is in doubt.

Mast cell sarcoma: new cases and literature review

Mast cell sarcoma (MCS) is a rare form of mastocytosis characterized by the presence of solid tumor(s) comprising malignant mast cells that harbor destructive infiltration capability and metastatic potential. Here, we present an extensive literature review and report on 23 cases of MCS, including 3 new cases from the French National Reference Center for Mastocytosis. From our analysis, it appears that MCS can occur at any age. It can manifest de novo or, to a lesser extent, may evolve from a previously established mastocytosis. Bone tumor is a frequent manifestation, and symptoms of mast cell activation are rare. Histological diagnosis can be difficult because MCS is frequently composed of highly atypical neoplastic mast cells and can thus mimic other tumors. Unexpectedly, the canonical KIT D816V mutation is found in only 21% of MCS; therefore, complete KIT gene sequencing is required. The prognosis of patients with MCS is poor, with a median survival time of less than 18 months, and progression to mast cell leukemia is not unusual. Because conventional chemotherapies usually fail, the role of targeted therapies and bone marrow transplantation warrants further investigation in such aggressive neoplasms.

Solitary Mastocytoma of the Eyelid in an Adult Patient With Prolidase Deficiency

Prolidase deficiency and solitary mastocytoma of the eyelid are both exceedingly rare. Prolidase deficiency is an inherited connective tissue disorder that has systemic sequelae, such as intractable skin ulceration, poor wound healing, recurrent infections, and intellectual impairment. Cutaneous mastocytoma is an isolated, aberrant cutaneous aggregation of mast cells. A case of an adult with severe prolidase deficiency who developed cutaneous mastocytoma of the eyelid was presented. To the authors' knowledge, adult-onset solitary mastocytoma of the eyelid has never been reported previously.

Imatinib in systemic mastocytosis: a phase IV clinical trial in patients lacking exon 17 KIT mutations and review of the literature

Resistance to imatinib has been recurrently reported in systemic mastocytosis (SM) carrying exon 17 KIT mutations. We evaluated the efficacy and safety of imatinib therapy in 10 adult SM patients lacking exon 17 KIT mutations, 9 of which fulfilled criteria for well-differentiated SM (WDSM). The World Health Organization 2008 disease categories among WDSM patients were mast cell (MC) leukemia (n = 3), indolent SM (n = 3) and cutaneous mastocytosis (n = 3); the remainder case had SM associated with a clonal haematological non-MC disease. Patients were given imatinib for 12 months -400 or 300 mg daily depending on the presence vs. absence of > 30% bone marrow (BM) MCs and/or signs of advanced disease-. Absence of exon 17 KIT mutations was confirmed in highly-purified BM MCs by peptide nucleic acid-mediated PCR, while mutations involving other exons were investigated by direct sequencing of purified BM MC DNA. Complete response (CR) was defined as resolution of BM MC infiltration, skin lesions, organomegalies and MC-mediator release-associated symptoms, plus normalization of serum tryptase. Criteria for partial response (PR) included ≥ 50% reduction in BM MC infiltration and improvement of skin lesions and/or organomegalies. Treatment was well-tolerated with an overall response rate of 50%, including early and sustained CR in four patients, three of whom had extracellular mutations of KIT, and PR in one case. This later patient and all non-responders (n = 5) showed wild-type KIT. These results together with previous data from the literature support the relevance of the KIT mutational status in selecting SM patients who are candidates for imatinib therapy.

Mast cell sarcoma: clinical management

Mast cell sarcoma is a disorder that results in abnormal mast cells as identified by morphology, special stains, and in some publications, c-kit mutation analysis. It affects animal species such as canines more commonly than humans. In humans it is a very rare condition, with variable clinical presentation. There is no standard therapy for the disorder. It can affect any age group. It is occasionally associated with systemic mastocytosis and/or urticaria pigmentosa. The prognosis of mast cell sarcoma in published literature is very poor in humans.

[Mastocytosis. Review of the literature and description of clinical cases]

The term mastocytosis (MC) encompasses a group of rare diseases characterized by the tumorous proliferation of clonal mast cells and the infiltration of one or several organs. The clinical picture of MC is extremely diverse from skin lesions that can spontaneously regress to the aggressive disease forms associated with organ dysfunction and short survival. Nowadays, the 2008 WHO classification identifies 7 MC subtypes. The disease is diagnosed on the basis of its clinical manifestations and detection of tumorous mast cell infiltrations via morphological, immunohistochemical, immunophenotypic, genetic, and molecular examinations. Abnormal mast cells are characterized by the atypical morphology and pathological expression of CD25 and CD2 antigens. Enhanced serum tryptase activity is a common sign in all MC subtypes. More than 90% of the patients have D816V KIT mutations in the mast cells. This paper reviews the literature. Three cases are described as a clinical example in patients with different MC subtypes.

Identification of KIT activating mutations in paediatric solitary mastocytoma

AIMS

Mastocytosis is an abnormal mast cell proliferation involving one or more organs, in particular the skin and bone marrow. In children, disease is usually limited to the skin, with three distinct clinical presentations: urticaria pigmentosa, diffuse cutaneous mastocytosis and solitary mastocytoma. Although the KIT D816V mutation is typically found in adult-onset mastocytosis, it is less commonly seen in childhood-onset mastocytosis, and the frequency of KIT mutations in paediatric solitary mastocytoma is poorly documented.

METHODS AND RESULTS

In this study we analysed KIT exons 8, 9, 11, 13 and 17 in nine cases of paediatric solitary mastocytoma using a laboratory-developed Sanger sequencing assay. A KIT mutation was identified in six cases (67%), including three with the D816V mutation typical of adult-onset disease, and another three with an internal tandem duplication (p.A502_Y503dup) in exon 9, previously described in gastrointestinal stromal tumour.

CONCLUSIONS

Paediatric solitary mastocytoma is frequently associated with KIT activating mutations, in keeping with a clonal process. KIT mutational status appears insufficient to explain the divergent biology of childhood and adult-onset disease.

Pediatric mast cell sarcoma of temporal bone with novel L799F (2395 C>T) KIT mutation, mimicking histiocytic neoplasm

Mast cell sarcoma (MCS) is an extremely rare neoplasm with a clinically aggressive course. Because of its rarity, its morphologic and molecular characteristics are still not well defined. We report a case of a 15-year-old girl with MCS of the temporal bone extending into the posterior fossa creating a mass effect. The lesion mimicked a histiocytic neoplasm morphologically, but showed a novel KIT missense mutation, L799F (2395 C>T). The KIT D816V mutation is frequently found in systemic mastocytosis, but it has not been documented in the few reported human MCS cases. However, 1 reported case of MCS has shown a different alteration in the KIT gene. Our case is the first MCS case with L799F mutation, located between the catalytic loop (790 to 797) and the activation loop (810 to 837) of the KIT gene, and only the second case of MCS with KIT mutation documented in the literature. Proximity of the L799F mutation to the enzymatic region of the KIT tyrosine kinase domain may induce resistance to tyrosine kinase inhibitors.

Mast cell sarcoma: a rare and potentially under-recognized diagnostic entity with specific therapeutic implications

Mast cell sarcoma is a rare, aggressive neoplasm composed of cytologically malignant mast cells presenting as a solitary mass. Previous descriptions of mast cell sarcoma have been limited to single case reports, and the pathologic features of this entity are not well known. Here, we report three new cases of mast cell sarcoma and review previously reported cases. Mast cell sarcoma has a characteristic morphology of medium-sized to large epithelioid cells, including bizarre multinucleated cells, and does not closely resemble either normal mast cells or the spindle cells of systemic mastocytosis. One of our three cases arose in a patient with a remote history of infantile cutaneous mastocytosis, an association also noted in one previous case report. None of our three cases were correctly diagnosed as mast cell neoplasms on initial pathological evaluation, suggesting that this entity may be under-recognized. Molecular testing of mast cell sarcoma has not thus far detected the imatinib-resistant KIT D816V mutation, suggesting that recognition of these cases may facilitate specific targeted therapy.

Diagnosis and treatment of mast cell disorders: practical recommendations

CONTEXT AND OBJECTIVE The term mastocytosis covers a group of rare disorders characterized by neoplastic proliferation and accumulation of clonal mast cells in one or more organs. The aim of this study was to assess the principal elements for diagnosing and treating these disorders. DESIGN AND SETTING Narrative review of the literature conducted at Grupo Fleury, São Paulo, Brazil. METHODS This study reviewed the scientific papers published in the PubMed, Embase (Excerpta Medica Database), Lilacs (Literatura Latino-Americana e do Caribe em Ciências da Saúde) and Cochrane Library databases that were identified using the search term "mastocytosis." RESULTS The clinical presentation of mastocytosis is remarkably heterogeneous and ranges from skin lesions that may regress spontaneously to aggressive forms associated with organ failure and short survival. Currently, seven subtypes of mastocytosis are recognized through the World Health Organization classification system for hematopoietic tumors. These disorders are diagnosed based on clinical manifestations and on identification of neoplastic mast cells using morphological, immunophenotypic, genetic and molecular methods. Abnormal mast cells display atypical and frequently spindle-shaped morphology, and aberrant expression of the CD25 and CD2 antigens. Elevation of serum tryptase is a common finding in some subtypes, and more than 90% of the patients present the D816V KIT mutation in mast cells. CONCLUSION Here, we described the most common signs and symptoms among patients with mastocytosis and suggested a practical approach for the diagnosis, classification and initial clinical treatment of mastocytosis.