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Solitary mastocytoma presenting in an adult: report and literature review of adult-onset solitary cutaneous mastocytoma with recommendations for evaluation and treatment

Background: Mastocytosis is either cutaneous (with skin-limited proliferation of mast cells) or systemic (with mast cells in extracutaneous sites). The onset of solitary mastocytoma in an adult is rare. Purpose: A woman with the new onset of solitary mastocytoma is described. The clinical features of patients with adult-onset solitary mastocytoma are summarized. Recommendations for the evaluation and treatment of individuals with adult-onset solitary mastocytoma are proposed. Methods: PubMed was searched with the key words: adult, CD2, CD25, cell, cutaneous, disease, KIT, KIT D816V, mast, mastocytoma, mutation, pigmentosa, solitary, tryptase, and urticarial. The papers generated by the search, and their references, were reviewed. Results: A 38-year-old Taiwanese woman presented with an asymptomatic brown patch, which morphologically mimicked a dysplastic nevus, on her right abdomen; biopsy demonstrated a solitary mastocytoma. Comprehensive evaluation (including serologic and bone marrow examination) excluded systemic mastocytosis and her residual mastocytoma is being monitored. Adult-onset solitary mastocytoma has been described in 16 patients. Lesions were either on the head and neck (5/14), torso (5/14) or extremities (4/14). Urtication following lesion rubbing was noted in 79% (11/14) of patients. Excision of the mastocytoma [75% (9/12)] was the most common treatment. Other management approaches included corticosteroids (topical or intralesional), antihistamines (systemic) or observation. Systemic symptoms were noted in 5 patients: flushing (3 women) and pruritus (3 women); gastrointestinal symptoms and headaches, flushing and/or anaphylaxis were each noted in one woman. None of the patients with adult-onset solitary mastocytoma had systemic mastocytosis; however, only 3 women were evaluated for systemic mastocytosis. Conclusions: Systemic mastocytosis is common in adults with new onset cutaneous mastocytosis. Therefore, a conservative work up for new onset solitary mastocytosis in adults is proposed to include complete blood cell counts, serum chemistries (including liver function tests), and serum tryptase level and bone marrow biopsy to evaluate for mast cell clusters, morphology and immunophenotype and KIT gene mutation in codon 816. Similar serologic testing should be considered annually for adult-onset solitary mastocytosis patients without systemic disease.


Introduction
Cutaneous mastocytosis can present as either urticarial pigmentosa (also referred to as maculopapular cutaneous mastocytosis), diffuse cutaneous mastocytosis, telangiectasia macularis perstans, and mastocytoma [1][2][3][4][5]. Mastocytomas are most commonly seen in infants (under 2 years of age) and children (ranging in age from 2 year to less than 16 years); many of these lesions improve spontaneously over

Case report
A healthy 38-year-old Taiwanese woman noticed four new asymptomatic pigmented lesions that had appeared during the prior year. She has no prior history of itching, flushing,   A mastocytoma is a localized dermal accumulation of mast cells that clinically presents as a reddish-brown macule or slightly raised papule; the lesion can be as large as 8 cm, thereby developing into a patch or nodule [7]. It usually presents as a single lesion; therefore, it has previously been

Major criteria
The presence of multifocal dense infiltrates of mast cells in the bone marrow or other extracutaneous organs, confirmed by special stains such as mast cell tryptase (greater than15 mast cells aggregating)

Minor criteria
Atypical mast cell morphology: in mast cell infiltrates in the bone marrow or other extracutaneous organs, greater than 25% of the mast cells are spindle-shaped or otherwise atypical; or in bone marrow smears, greater than 25% of the mast cells are spindle-shaped or otherwise atypical Aberrant mast cell immunophenotype: mast cells in extracutaneous organs (CD117) co-express either CD2 or CD25 or both, as determined by flow cytometry

Activating point mutation of KIT in codon 816 is present in extracutaneous organs
Baseline serum tryptase level is persistently elevated (greater than 20 ng/ml); this does not count in patients who have an associated clonal hematologic non-mast cell disease (AHNMD) [a] The diagnosis of systemic mastocytosis is fulfilled either by: (1) the presence of the major criterion plus one minor criterion or (2) the presence of at least three minor criterion. [c] He received 20 mg/ml of kenalog into the lesion every 3 weeks for 2 injections; there was decreased itching of the lesion, but no change in its size. Also, the positive urtication (Darier's sign) of the lesion persisted.
[d] The pathology report read: "The H. and E. stain is not diagnostic. With toluidine blue the upper cutis shows about 10 mast cells per high power field, somewhat concentrated around the blood vessels. " The patient was presented by Dr. Jesse A. Tolmach as "urticaria pigmentosa (solitary lesion in adult) at the NewYork Academy of Medicine, Section of Dermatology and Syphilology meeting on March 6, 1962 . The unopposed comments of Dr. Arthur Bernard Hyman were: " . . . where no other pathology is found and there are 10 mast cells per high-power field, it is considered, according to our present arbitrary standards, as more than sufficient to make a diagnosis and confirms a diagnosis of urticarial pigmentosa.
[e] The patient also had severe prolidase deficiency. He had 2 adjacent solitary mastocytomas; the larger (inferior) measured 5 x 4 mm and the superior lesion was smaller.
[f] The patient had facial flushing and generalized itching.
[g] The patient had facial flushing and generalized itching every 2-3 months; the "itching was suppressed only with continuous use of systemic antihistaminics and topical steroids, later intralesional steroids relieved pruritus for 6 months. " [h] The patient had one episode of gastrointestinal distress with severe nausea and vomiting, diarrhea, and abdominal pain. Complete blood cell counts, platelet counts and liver function tests were normal and stool guiac was negative.
[i] She had intense bouts of pruritus every 3-4 weeks. She was initially treated symptomatically with systemic antihistamines and topical corticosteroids with a partial response. Subsequently, an excisional biopsy was performed.
[j] She had a 10-year history of headaches, flushing, and anaphylaxis triggered by exercise, stress, heat or scalp friction. The patient experienced no flushing or anaphylaxis while pregnant, but her symptoms returned after delivery. The subcutaneous scalp mass was excised; postoperatively, she had no further symptoms at 27 months follow-up.
women) [10,16]. One of the women had experienced only one episode of gastrointestinal distress characterized by severe nausea and vomiting, diarrhea and abdominal pain [11].
Another woman had generalized symptoms of 10 years duration consisting of headaches, flushing and anaphylaxis that were triggered by exercise, stress, heat or scalp friction; her mastocytoma presented as a subcutaneous scalp nodule [7].
All patients had hematoxylin and eosin stained tissue biopsy confirmation of their mastocytoma. The mast cells were typically present in the upper dermis-in either nodular or interstitial or sheet-like infiltrates and/or around blood vessels. They presented as monomorphic mononuclear cells with abundant pale basophilic staining, granule containing, cytoplasm. Special histopathologic and/or immunohistochemical stains were used to confirm the suspected diagnosis of mast cells: azure A [15], CD25 (inerleukin-2 receptor alpha chain) [12], Giemsa [7,8], kit (CD117, the receptor for stem cell factor) [12], toluidine blue [8,9,14] and tryptase [7,12,current report]; the granules in the cytoplasm were clearly demonstrated using either Giemsa and toluidine blue stain [8]. In some of the patients lymphocytes [7] or eosinophils [14,15] were also present in the dermal infiltrate.
The management of the solitary mastocytoma was described for 12 patients. Excision (9/12, 75%) was the most common treatment. This was either performed as an excisional biopsy during the initial evaluation [8,[10][11][12]15,16] or subsequently [7,14]. Two individuals were initially treated with oral antihistamines and topical corticosteroids [10,16]; the lesions were subsequently treated with either excision [10] or an intralesional corticosteroid injection [16]. The woman in the current report received no additional treatment following her biopsy; her lesion was asymptomatic and she remains free of symptoms.
Intralesional corticosteroids have been used to successfully treat solitary mastocytomas in infants [22]. The mastocytoma was treated with intralesional corticosteroids in two patients [14,16]. A 30-year-old Indian man had two injections-three weeks apart-of 20 mg/ml of Kenalog®, that resulted in decreased itching but neither size change nor ceasing of urtication of the lesion [14]. Also, a 22-year-old Indian woman whose itching was relieved for six months following intralesional corticosteroids; her pruritus previously has only been suppressed with continuous use of systemic antihistamines and topical corticosteroids [16].
In addition to the reported patient, evaluation for systemic mastocytosis was only preformed in 2 patients [7,11]. One patient was a 33-year-old Caucasian woman who had experienced one episode of gastrointestinal distress (associated with severe nausea and vomiting, diarrhea, and abdominal pain) two years earlier. She had a complete blood cell count, platelet count and liver function tests that were normal and a stool guaiac examination that was negative [11].
The onset age of the mastocytoma was the same age as the diagnosis of the lesion in five individuals: three men and two women. A delay from 1 year to 30 years (median, 4 years) occurred between the age when the other nine patients initially recognized the skin lesion and the diagnosis was established. For the five men, between 2 to 30 years (median, 5 years) passed between the onset age and diagnosis age of their mastocytoma. For the four women, between 1 to 10 years (median, 2 years) passed between the onset age and diagnosis age of their mastocytoma.
The clinical appearance of the mastocytoma varied from a patch to a plaque to a nodule. The color varied from brown to brown-red to red or pink; part of one woman's lesion was yellow. Three of the men had lesions that were either hypopigmented or non-pigmented.
The women in this report had a brown patch that was clinically suspected to be a dysplastic nevus; solitary [11] and multiple [17,18] mastocytomas have previously been misinterpreted as a melanocytic nevus. The hyperpigmentation associated with mastocytomas has been postulated to be secondary to induction of melanocytes by increased local concentrations of soluble mast cell growth factors from the mast cell lesions of cutaneous mastocytosis [13,[19][20][21].
In addition to a melanocytic nevus (or a dysplastic nevus [current report] or Spitz nevus [11], the clinical differential diagnosis of solitary mastocytoma includes chronic arthropod bite reaction [15], cyst [8], granuloma [8], hidrocystoma [15], leukemia cutis [11], and xanthogranuloma [11]. Generalized symptoms associated with the solitary mastocytoma were observed in 31% (5/16) of the individuals [7,10,11,16]. All of the patients were women: three Indian [10,16], one Caucasian [11], and one whose race was not reported [7]. The symptoms most commonly occurring included flushing (three women) [7,16] and pruritus (three row should be evaluated for c-KIT mutation at codon 816; in addition the bone marrow aspirate and biopsy should be examined for foci of greater than or equal to 15 mast cells, morphology of the mast cells, and expression of CD2 and/or CD25 by bone marrow mast cells [3,4]. If the initial evaluation for systemic mastocytosis is negative, annual testing for complete blood cell and platelet counts, serum chemistries including liver function tests, and a serum tryptase level should be considered.

Conclusions
A mastocytoma presents as a reddish-brown papule that con- flushing triggered by exercise, heat, scalp friction or stress [7].
She had a major criterion for the diagnosis of systemic mastocytosis (a few clusters of greater than 15 mast cells were present on the bone marrow biopsy specimen), but did not fulfill any of the diagnostic minor criteria (Table 1)   In summary, it is proposed that the initial work up for adult-onset solitary mastocytoma would include a complete blood cell count, serum chemistries (including liver function tests), and serum tryptase level; serologic evaluation for D816V mutation in the KIT gene should also be considered.
In addition, a bone marrow biopsy to assess, not only mast cell clusters, morphology and immunophenotype, but also KIT gene mutation in codon 816, should be performed. In patients with adult-onset solitary mastocytoma without systemic mastocytosis, yearly blood tests to evaluate complete blood cell counts, chemistries (including liver function tests), and tryptase level should be considered.