Fig 1. A 1-cm plaque with central depression and telan-giectasia on glabella.

Fig 2. Histopathologic specimen obtained from Mohsmicrographic surgery shows two distinct parts locatedadjacently. One side of the specimen showed randomlyarranged narrow strands of basaloid cells and epithelialcysts containing keratin material in a fibrous stroma(arrow). The other side of the specimen shows a well-circumscribed nodular tumor composed of variously sizedtubular and branching lumina lined by two layers ofepithelial cells and a small cellular aggregate of epithelialcells in fibromyxoid stroma (arrowhead ). (Hematoxylin-eosin stain; original magnification: 31.5.)

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8. Thang OHD, Jaspars EH, ter Wee PM. Necrotising mastitis

caused by calciphylaxis. Nephrol Dial Transplant 2006;

21:2020-1.

doi:10.1016/j.jaad.2010.08.005

Collision of two rare adnexal tumors withfolliculosebaceous differentiation

To the Editor: Cutaneous collision tumor, the coex-istence of more than one neoplasm in a singlecutaneous specimen, is unusual. Most of the collisiontumors are accidental, such as a combination of basalcell carcinoma and melanocytic nevus; however,some of them may arise from the involvement ofrelated cell types in cases of adnexal tumors.However, to our knowledge the combination ofdesmoplastic trichoepithelioma (DTE) and chon-droid syringoma (CS) has never been reported.

A 38-year-old man presented with a 1-cm plaquewith central depression and telangiectasia onthe glabella that had been present for 10 years(Fig 1). He had no relevant medical or family history.Histopathologic features of the punch biopsy spec-imen were consistent with DTE. Mohs micrographicsurgery (MMS) was performed to remove the DTEcompletely. Histopathologically, the specimen ob-tained by MMS showed two distinct parts locatedadjacently (Fig 2). Half of the specimen was consis-tent with DTE. However, the other side of thespecimen showed a well-circumscribed nodular tu-mor, which was consistent with CS. In addition, therewas evidence of follicular differentiation, such asseveral nests of peripherally palisading undifferenti-ated basophilic cells, clear cell nests similar to theouter root sheath, dermal papillae-like structures,and pilomatricomal differentiation with shadowcells. A final diagnosis of DTE associated with CSwas made.

Considering their origins from similar cell types,the collision tumor composed of two or moreadnexal tumors is plausible and could give us ahint of the pathogenesis. DTE and CS are rare benigncutaneous adnexal tumors. The former (DTE) showsdifferentiation toward the hair follicle and sometimessebaceous gland, and the latter (CS) shows the morecommon apocrine differentiation or the rare eccrinedifferentiation in a mesenchymal stroma, sometimeswith hair follicular or sebaceous differentation.1 DTEhas rarely been reported in association with a nevusand an epidermal cyst. CS has never been reported inassociation with other distinct tumors except in onecase in which CS was associated with eccrine spi-radenoma in a blaschkoid distribution.

Benign adnexal tumors with a variable spectrumof differentiation, including follicular, sebaceous,

apocrine, and eccrine features, have been reported.2

Considering their similar folliculosebaceous differ-entiation features, the collision tumor of DTE and CScould not be attributed tomere chance. One possiblemechanism is that DTE and CS arise frommultipotentstem cells.3 The origin of DTE is not conclusive, but itwas suggested that the cells in DTE are originatedfrom the bulge region and are in close relation withthe pluripotent basal cells in the outer root sheath.4

The origin of CS is also still uncertain, but ectodermalpluripotent cells were suggested as the possibleorigin.5 Recently, Misago and Narasawa6 demon-strated substantial cytokeratin 15 expression in theapocrine-type chondroid syringoma with folliculo-sebaceous differentiation and suggested that it isderived from multipotent epithelial stem cells in thefollicular bulge. Therefore it is reasonable that twobenign adnexal tumors with differentiations from thefolliculosebaceous apocrine unit arise from multi-potent stem cells in the follicular bulge region.

Fig 1. A, Patient’s axilla before treatment with pravastatin.B, Patient’s axilla after treatment with pravastatin.

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In conclusion, we present a case of a collisiontumor composed of rare benign tumors; DTE and CS,which may give us a clue regarding the possibleorigin of adnexal tumors.

Jihyun Kim, MD, Hyo-Jin Roh, MD, Kee YangChung, MD, PhD, and Mi Ryung Roh, MD

Department of Dermatology and Cutaneous Biol-ogy Research Institute, Yonsei University Collegeof Medicine, Seoul, Korea

Funding sources: None.

Conflicts of interest: None declared.

Correspondence to: Mi Ryung Roh, MD, Depart-ment of Dermatology and Cutaneous BiologyResearch Institute, Yonsei University College ofMedicine, 712 Eonjuro, Gangnam-gu, Seoul,Korea, 135-720

E-mail: karenroh@yuhs.ac

REFERENCES

1. Kazakov DV, Belousova IE, Bisceglia M, Calonje E, Emberger M,

Grayson W, et al. Apocrine mixed tumor of the skin (‘‘mixed

tumor of the folliculosebaceous-apocrine complex’’). Spectrum

of differentiations and metaplastic changes in the epithelial,

myoepithelial, and stromal components based on a histo-

pathologic study of 244 cases. J Am Acad Dermatol

2007;57:467-83.

2. Wong TY, Suster S, Cheek RF, Mihm MC Jr. Benign cutaneous

adnexal tumors with combined folliculosebaceous, apocrine,

and eccrine differentiation. Clinicopathologic and immunohis-

tochemical study of eight cases. Am J Dermatopathol

1996;18:124-36.

3. Perez-Losada J, Balmain A. Stem-cell hierarchy in skin cancer.

Nat Rev Cancer 2003;3:434-43.

4. Yamamoto O, Hamada T, Doi Y, Sasaguri Y, Hashimoto H.

Immunohistochemical and ultrastructural observations of

desmoplastic trichoepithelioma with a special reference to a

morphological comparison with normal apocrine acrosyrin-

geum. J Cutan Pathol 2002;29:15-26.

5. Mills SE. Mixed tumor of the skin: a model of divergent

differentiation. J Cutan Pathol 1984;11:382-6.

6. Misago N, Narisawa Y. Cytokeratin 15 expression in apocrine

mixed tumors of the skin and other benign neoplasms with

apocrine differentiation. J Dermatol 2006;33:2-9.

doi:10.1016/j.jaad.2010.08.020

Treatment of indeterminate cell histiocytosiswith pravastatin

To the Editor: A 41-year-old woman with a history ofsystemic lupus erythematosus presented to our clinicwith a several-month history of a diffuse papulareruption, arising primarily in her axillae, groin,submammary regions, and upper cutaneous lip.The lesions were yellow brown and minimally pru-ritic (Fig 1,A). Initial labworkwas significant only formodestly elevated total cholesterol and triglycerides.

Punch biopsy revealed a monomorphous dermalinfiltrate of histiocytes admixed with multinucleatedgiant cells, some with Touton morphology andabundant cytoplasmic lipid. By immunohistochem-istry, the histiocytes were strongly positive for CD68,focally positive for CD1a, and weakly S-100 positive(Fig 2, A and B). These immunohistochemical fea-tures were consistent with a final diagnosis of inde-terminate cell histiocytosis (ICH), although clinicallyresembling xanthoma disseminatum.

Despite the patient being only modestly dyslipi-demic, she was empirically started on 20 mg of oralpravastatin daily. The patient noted significantimprovement in her lesions as soon as 6 weeksafter initiation of treatment. Her pravastatin dosewas gradually increased to a maximum dose of60 mg daily. Over her 2½ years of treatment, herlesions continued to soften, flatten, lighten, andmany disappeared altogether, without develop-ment of new lesions (Fig 1, B). The patient’s totaland low-density lipoprotein cholesterol decreasedto normal levels over the course of treatment. Thepatient is currently on a regimen of 60 mg ofpravastatin.

ICH is a rare proliferative disorder of histiocytespresenting as a generalized papular eruption.Indeterminate cells are described as dendritic cellshistologically and immunohistochemically resem-bling Langerhans cells because of their expressionof CD1a and S-100, but lacking the definitiveBirbeck granule.1 Our main differential diagnoseswere xanthoma disseminatum, generalized eruptivehistiocytosis, and multicentric reticulohistiocytosis,which is known to be associated with lupus eryth-ematosus in a small percentage of cases. However,the positive ICH staining of CD68, CD1a, and S-100allowed us to make the diagnosis of ICH overxanthoma disseminatum or another nonLangerhans