Subcutaneus Nodules on the abdomen.

What is your diagnosis?

F. Peral Rubio, M.D.Department of Dermatology

Hospital Universitario Virgen Macarena, Seville, Spain.

www.dermatoblog.com

Subcutaneus Nodules on the abdomen

A 30-year-old woman presents with multiple asymptomatic subcutaneous nodules, round-to-oval, well-defined, smooth-surfaced, yellow to skin-colored.

5-10 mm diameter firm papules scattered on the abdomen.

The lesions have been present for about 10 years.

Subcutaneus Nodules on the abdomen

Biopsy specimens shows well-encapsulated dermal cysts with infolded walls lined by stratified squamous epithelium without a granular layer.

Sebaceous gland lobules are found within the cyst wall.

Subcutaneus Nodules on the abdomen.

What is your diagnosis?

F. Peral Rubio, M.D.Department of Dermatology

Hospital Universitario Virgen Macarena, Seville, Spain.

www.dermatoblog.com

hospital with asymptomatic subcutaneous nodules on her forearms. She first noticed the subcutaneous nodules 10 years previously, and they had gradually increased in both size and number. They were not associated with any pain or tenderness. Her family history and past clinical history were unremarkable. Physical examination revealed multiple, mobile, well-defined, elastic-hard, 5–10 mm subcutaneous nodules on the flexor surface of the forearms; 8 on the right and 3 on the left (Fig. 1). There were no other lesions except for the forearms and no nail changes. Clinically, the lesions were initially thought to be multiple lipomas and an excisional biopsy was performed to confirm the suspected diagnosis. Upon biopsy, a well-circumscribed ovoid cyst was isolated in the superficial subcutaneous fat layer. The cyst contained yellow creamy material. Biopsy specimen showed a well-encapsulated subcutaneous cyst with infolded walls lined by squamous epithelium without a granular layer. Sebaceous gland lobules are found within the cyst wall (Fig. 2). From these findings, the diagnosis of SM was finally made.

Fig. 2. Histopathological features. Well-encapsulated subcutaneous cysts with

infolded walls lined by stratified squamous epithelium without a granular

layer (haematoxylin-eosin (H&E) stain; original magnification, ×10). Inset

shows sebaceous gland lobules within the cyst wall. (H&E stain; original

DISCUSSION This case of SM is unique due to (i) its acral distribution and (ii) presentation as subcutaneous nodules. SM can appear anywhere on the body but is more common in areas where the pilosebaceous apparatus is well developed, such as the trunk, neck, axilla, inguinal region, scalp and the proximal extremities. Acral SM, which involves the extremities more prominent than the trunk, is rare and has been described in only 2 reports (1, 2). Chu (1) reported a 25-year-old man with a 20-year history of asymptomatic nodules on the arms and chest, which showed findings consistent with SM upon histopathological analysis. The patient had no family history and no nail changes like in pachonychia congenita (PC). Rollins et al. (2) reported a 32-yearold Filipino woman with an 8-year history of multiple cystic nodules on the distal upper and lower extremities. The patient’s family history was insignificant, and she had no changes in the nails. With regard to the depth of the lesion, steatocystoma is thought to result from a hamartomatous malformation of the pilosebaceous duct junction and is usually located in the mid-dermis (3). In our case, the lesions were palpated as subcutaneous nodules mimicking multiple lipomas, which is not a well-described presentation in textbook SM references. Dermatologists should be aware of that SM may present as acral subcutaneous nodules. Covello et al. (4) reported that keratin 17 mutations commonly underlie both PC type-2 and SM, however,

they could not find a correlation between genotype and phenotype. Furthermore, they could not detect any keratin 17 mutations in sporadic cases of SM (4). These observations suggest a multifactorial basis, including both genetic and environmental factors, for this disease. The reason why our case exhibited an acral distribution and presentation as subcutaneous nodules is not understood, but a combination of genetic factors including keratin 17 abnormalities, other keratin defects and/or environmental factors, may be involved in the unique clinical appearance. REFERENCES 1. Chu DH. Steatocystoma multiplex. Dermatol Online J 2003; 9: 18. 2. Rollins T, Levin RM, Heymann WR. Acral steatocystoma multiplex. J Am Acad Dermatol 2000; 43: 396–399. 3. Sabater-Marco V, Perez-Ferriols A. Steatocystoma multiplex with smooth muscle. A hamartoma of the pilosebaceous apparatus. Am J Dermatopathol 1996; 18: 548–550. 4. Covello SP, Smith FJ, Sillevis Smitt JH, Paller AS, Munro CS, Jonkman MF, et al. Keratin 17 mutations cause either steatocystoma multiplex or pachyonychia congenita type 2. Br J Dermatol 1998; 139: 475–480. Acta

A 70-year-old man presents with multiple asymptomatic, round-to-oval, well-defined, smooth-surfaced, yellow to skin-colored, 5-11-mm diameter firm papules scattered on the scalp; the lesions have been present for about 30 years (Fig. 1). There are no similar lesions on the other parts of the body. The smaller papules are skin-colored and, when punctured, discharge a clear or milky, oily liquid (Fig. 2). The larger lesions are yellow and, when punctured, discharge a yellow, creamy-to-cheesy material (Fig. 3). On examination, he also has Hamilton type VIII androgenetic alopecia. There is no history of erythema, tenderness, or infection of the lesions. There is no family history of similar lesions.

Biopsy specimens shows well-encapsulated dermal cysts with infolded walls lined by stratified squamous epithelium without a granular layer. Sebaceous gland lobules are found within the cyst wall. The smaller, skin-colored lesions have atrophic walls with from two to five layers of flat epithelial cells and empty lumina. The larger, yellow lesions have from three to five layers of cuboidal epithelial cells with a thin layer of crenulated, eosinophilic material on the luminal surface and a little eosinophilic horny material in some parts of the lumen (Fig. 4). No connection between the cyst walls and overlying epidermis is found in the serial sections.

In contrast with the typical steatocystoma multiplex patients, lesions are limited to the scalp in our case. There have been only a few cases with such a limited distribution [4 6, 9, 10] Table 1 presents a review of the English-language literature of the published cases of localized forms of steatocystoma multiplex. In the reported cases of localized steatocystoma multiplex, the lesions are confined to the head and neck or genitalia. The terms facial papular variant of steatocystoma multiplex and sebocystomatosis have been used to describe some of these localized forms as distinctive variants of the disease [3, 11, 12]. However, involvement of these areas is not infrequent in typical cases of steatocystoma multiplex [1]. There are reports of the cases with steatocystoma multiplex involving predominantly the face or head and neck with scattered lesions on the trunk [13]. The pathological and clinical features of the localized forms are not different from typical cases. Therefore, we believe that the localized forms of steatocystoma multiplex are not distinctive variants of the disease. Steatocystoma multiplex should be considered as a spectrum with different variations in anatomical distribution.

A 21-year-old male presented with a 1-year history of multiple dark bumps on his chest and abdomen since his deployment to Kuwait. These lesions were itchy and became worse in hot climates but did not worsen in cooler temperatures. An allergic reaction to his dog tag necklace was deemed less likely because the affected area persisted and grew larger after removal of the presumed antigen. Treatment with over-the-counter acne medications did not help.

Physical examination revealed multiple bluish-black superficial and deep subcutaneous papules in clusters on the chest (Fig. 1). The clinical differential diagnosis was comedonal acne and SM. A biopsy specimen showed cyst without cyst contents and sebaceous glands within and close to the cyst wall (Fig. 2). The cyst wall was composed of stratified squamous epithelium without a granular layer, and a thick, homogenous, eosinophilic layer protruding towards the cyst lumen (Fig. 3).

An empty cyst with sebaceous lobules within and close to the cyst wall. (H & E, original magnification

The cyst wall shows squamous epithelium without a granular layer, a sebaceous lobule within the cyst wall and an eosinophilic thick horny layer. (H & E, original magnification × 100).