1/9. Alteration of mast cell proliferation/apoptosis and expression of stem cell factor in the regression of mastocytoma--report of a case and a serial immunohistochemical study. BACKGROUND: Spontaneous regression of solitary mastocytoma is a well-described phenomenon, but its mechanism is unknown. methods: Serial-section immunohistochemical analyses were performed on biopsies of a mastocytoma from a Japanese child during the proliferation stage (PS, 7 months of age) and the regression stage (RS, 5 years old). RESULTS: Mast cell (MC) density in RS was markedly decreased (406 cells/mm2) compared to that in PS (3554 cells/mm2). MCs in RS were larger than those in PS. With proliferative cell nuclear antigen (PCNA) staining, 1.7% MCs were positive in PS, whereas no positive MCs were seen in RS. TUNEL-labeling index (LI) in RS (2.8%) increased 1.5-fold in PS (1.9%). With stem cell factor (SCF) staining, 57% of lesional MCs in RS revealed strong cytoplasmic immunoreactivity, whereas only 9% of MCs were positive in PS. Epidermal SCF reactivity was found as intracellular and intercellular patterns in both PS and RS. CONCLUSIONS: Loss of MC proliferating activity, an increase in apoptotic MCs, and increased expression of SCF in remaining MCs in RS may play a role in the involution of mastocytomas. ( info) |
2/9. Solitary mastocytoma of the vulva: report of a case. A solitary mastocytoma was encountered involving the left labium majus of a 6-year-old girl. Tumor cells contained numerous cytoplasmic metachromatic granules that were immunoreactive for tryptase and CD117. As mast cells are difficult to recognize on routine stains, identification of mast cell lesions requires a high degree of suspicion. This is probably the first reported case of mastocytoma occurring in the vulva. ( info) |
3/9. flushing due to solitary cutaneous mastocytoma can be prevented by hydrocolloid dressings. Solitary mastocytomas occur commonly and can occasionally be associated with troublesome flushing related to rubbing. We report a child with a solitary mastocytoma who repeatedly and reproducibly caused flushing only with rubbing and scratching. Conventional treatment with antihistamines was not completely effective and caused sedation. A trial application of double-layer hydrocolloid dressing led to complete abolition of flushing episodes until the child reached an age where he could peel off the dressings. This treatment is particularly suited to very young children with solitary mastocytomas whose parents do not feel comfortable with antihistamine treatment, topical or intralesional corticosteroids, or surgical interventions. This treatment may be used alone or in conjunction with conventional therapy where there has been a failure to achieve complete control of flushing and/or blistering. ( info) |
4/9. Solitary mastocytoma successfully treated with a moderate potency topical steroid. We report a case of solitary mastocytoma in a child which was successfully treated with a topical steroid of moderate potency. The patient was an 18-month-old girl who presented with localized oval shape yellowish to hyperpigmented lesion on the medial aspect of her right forearm noticed accidentally by the parents since the age of 6 months. The lesion was observed to get urticated mainly after bathing, toweling, and scratching of the area, associated with reddening and itching confined to the lesion (Figure 1). No other area of the body was affected with any similar lesion. Examination of the skin revealed a yellow-tan oval shape patch 1 x 3 cm in diameter which was firm to the touch with intact overlying skin. The lesion became swollen and itchy when it was rubbed vigorously (positive Darier's sign). Systemic examination was unremarkable. The patient investigations including complete blood count, routine biochemical data, plasma histamine level, and urinalysis were within normal levels. Skin biopsy was cancelled because the parents refused, so our clinical diagnosis was solitary mastocytoma even though it was not confirmed histologically. We started the patient on a moderate potency corticosteroid (betamethasone valerate 0.1% cream) twice a day for six weeks after which the lesion became softer with a weak Darier's sign. This treatment was continued for another four months which led to resolution of the lesion with residual hyperpigmentation, negative Darier's sign, and no signs of atrophy (Figure 2). Follow up of the patient for another 8 weeks without treatment did not reveal any recurrence of the lesion. ( info) |
5/9. Electron microscopic study in a case of solitary mastocytoma. The authors report a solitary mastocytoma with a solitary red infiltrated plaque on the dorsum of the right foot for 2 months. Histologically there were numerous mast cells infiltrating the dermis. Electron microscopy revealed CLCs located in phagosomes of activated macrophages as well as in the stromal tissue, close association between CLCs formation and damaged eosinophils was documented Charcot-Leyden crystals (CLCs) have been found in many conditions associated with eosinophilia, but their occurrence in skin diseases is very rare. These occurrences showed the evidence that the formation of CLCs in a mastocytoma correlated to the individual and related to the biology of mast cells, basophils, eosinophils and macrophages. phagosomes probably acted as the localization of CLCs formation. The pathological role of CLCs in a mastocytoma needs further investigation. ( info) |
6/9. An unusual mastocytoma with massive eosinophilic infiltration: identification with immunohistochemistry. A cutaneous mastocytoma excised from a 6-month-old male infant was found to have unusual massive eosinophilic infiltrates. The mast cells were identified with the aid of immunohistochemistry with antibodies to tryptase and KIT protein (CD117). Massive eosinophilic infiltration in a cutaneous tumor could be a diagnostic clue of an eosinophil-rich mastocytoma. ( info) |
| A unique combined mastocytoma-junctional nevus presented as a 4-mm dark brown macule in the axilla of a 57-year-old white female. Histopathologic examination revealed a proliferation of mast cells partially or completely filling the dermal papillae, hyperpigmentation of the basal keratinocytes and mildly increased basal melanocytes. Overlying the mast cell proliferation, pigmented junctional nevus nests were present. The mast cells were strongly positive with Giemsa stain and mast cell tryptase immunohistochemical stain; nevomelanocytic cells were negative. Nevomelanocytes were strongly immunoreactive for S100, HMB-45, Mart-1, and tyrosinase; mast cells were negative. The clinicopathologic features suggested a synchronous proliferation of 2 cell types in the same small cutaneous field rather than a collision tumor. While the cutaneous mast cells probably originated as a disseminated clone, it is postulated that local mast cell growth factor induced nevomelanocytic proliferation and modulated mast cell growth. In fact, the tumor exhibited strong immunoreactivity for the mast cell growth factor receptor (CD117) in mast cells, basal melanocytes, and nevus nests. The incidence of dual mast cell-melanocytic tumors appears to be very low, as only 3 total cases have now been reported. However, since in patients with multiple mastocytomas only a small fraction of lesions are biopsied, the true incidence may be higher than supposed. ( info) |
8/9. Congenital smooth muscle hamartoma: the importance of differentiation from melanocytic nevi. Congenital smooth muscle hamartoma (CSMH) is a rare cutaneous lesion commonly seen on the trunk or extremities as a localized skin-colored or mildly hyperpigmented and irregularly shaped patch or plaque with prominent vellus hairs. Histologically, CSMH is characterized by the proliferation of intersecting bundles of smooth muscle. The clinical differential diagnosis of CSMH includes congenital melanocytic (pigmented) nevus, Becker's melanosis, solitary mastocytoma, piloleiomyoma, cafe-au-lait spots, and nevus pilosus. Differentiating CSMH from a congenital melanocytic nevus avoids the unnecessary excision of this benign condition. ( info) |
9/9. Midline cutaneous lumbosacral lesions: not always a sign of occult spinal dysraphism. OBJECTIVE: The authors report two unusual cases of extraspinal midline lumbosacral lesions that resembled the usual skin markers of occult spina bifida. patients AND methods: The pathological diagnosis of the masses was plexiform neurofibroma and mastocytoma, respectively. RESULTS: Some lesions, as those we are reporting, although occurring at the lumbosacral midline, do not necessarily belong to occult spinal dysraphism, as was initially suspected. Plexiform neurofibroma and skin mastocytoma are very rare indeed in this spinal location. CONCLUSION: The two cases represent an important addition to the differential diagnosis of a congenital dorsal midline mass. ( info) |